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46
Sep 19, 2013
09/13
by
O. J. Taylor; A. Carrington; J. A. Schlueter
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We present high resolution heat capacity measurements for the organic superconductors kappa-(ET)_2Cu[N(CN)_2]Br and kappa-(ET)_2Cu(NCS)_2 in fields up to 14 T. We use the high field data to determine the normal state specific heat and hence extract the behavior of the electronic specific heat C_{el} in the superconducting state in zero and finite fields. We find that in both materials for T/T_c
Source: http://arxiv.org/abs/cond-mat/0703673v1
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56
Sep 23, 2013
09/13
by
O. J. Taylor; A. Carrington; J. A. Schlueter
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eye 56
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We present measurements of the low temperature specific heat of single crystals of kappa-(ET)_2Cu[N(CN)_2]Br as a function of the cooling rate through the glasslike structure transition at $\sim$ 80K. We find that rapid cooling produces a small ( < 4%) decrease in the superconducting transition temperature accompanied by a substantial (up to 50%) decrease in the normal-state electronic specific heat. A natural explanation of our data is that there is a macroscopic phase separation between...
Source: http://arxiv.org/abs/0801.2502v1
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55
Sep 21, 2013
09/13
by
L. Malone; O. J. Taylor; J. A. Schlueter; A. Carrington
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eye 55
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We report specific heat measurements of the organic superconductors $\kappa$-(ET)$_2$Cu(NCS)$_2$ and $\kappa$-(ET)$_2$Cu[N(CN)$_2$]Br. When the magnetic field is rotated in the highly conducting planes at low temperature ($T\simeq 0.4$ K), we observe clear oscillations of specific heat which have a strong fourfold component. The observed strong field and temperature dependence of this fourfold component identifies it as originating from nodes in the superconducting energy gap which point along...
Source: http://arxiv.org/abs/0905.2342v2
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73
Jul 20, 2013
07/13
by
T. Lancaster; S. J. Blundell; F. L. Pratt; J. A. Schlueter
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eye 73
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A muon-spin relaxation (muSR) investigation is presented for the molecular superconductor kappa-(BEDT-TTF)2Cu[N(CN)2Br]. Evidence is found for low-temperature phase-separation, with only a fraction of the sample showing a superconducting signal, even for slow cooling. Rapid cooling reduces the superconducting fraction still further. For the superconducting phase, the in-plane penetration depth is measured to be lambda_{parallel} = 0.47(1) mu m and evidence is seen for a vortex decoupling...
Source: http://arxiv.org/abs/1007.0148v1
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50
Sep 19, 2013
09/13
by
R. S. Edwards; A. Narduzzo; J. Singleton; A. Ardavan; J. A. Schlueter
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We have measured details of the quasi one-dimensional Fermi-surface sections in the organic superconductor kappa-(BEDT-TTF)_2 Cu(NCS)_2 and its deuterated analogue using angle-dependent millimetre-wave techniques. There are significant differences in the corrugations of the Fermi surfaces in the deuterated and undeuterated salts. We suggest that this is important in understanding the inverse isotope effect, where the superconducting transition temperature rises on deuteration. The data support...
Source: http://arxiv.org/abs/cond-mat/0208086v1
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6.0
Jun 28, 2018
06/18
by
G. Koutroulakis; H. Kühne; J. A. Schlueter; J. Wosnitza; S. E. Brown
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eye 6
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Quasi-two dimensional superconductors with sufficiently weak interlayer coupling allow magnetic flux to penetrate in the form of Josephson vortices for in-plane applied magnetic fields. A consequence is the dominance of the Zeeman interaction over orbital effects. In the clean limit, the normal state is favored over superconductivity for fields greater than the paramagnetic limiting field, unless an intermediate, inhomogeneous state is stabilized. Presented here are nuclear magnetic resonance...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1511.03758
3
3.0
Jun 30, 2018
06/18
by
K. G. Padmalekha; M. Blankenhorn; T. Ivek; L. Bogani; J. A. Schlueter; M. Dressel
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eye 3
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The organic conductor $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_{3}$ seems to form a quantum spin liquid, although at low temperatures unusual properties are seen in the charge, spin and lattice degrees of freedom. Here we report results of X-band ESR studies of $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_{3}$ single crystals as a function of temperature and angle. We find indications of two anisotropic relaxation mechanisms at low temperatures and compare them to the spin-liquid behavior observed in other...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1409.2033
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61
Sep 23, 2013
09/13
by
F. Zuo; J. S. Brooks; Ross H. McKenzie; J. A. Schlueter; Jack M. Williams
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eye 61
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We report detailed measurements of the interlayer magnetoresistance of the layered organic superconductor $\kappa -(BEDT-TTF)_2Cu(SCN)_2$ for temperatures down to 0.5 K and fields up to 30 tesla. The upper critical field is determined from the resistive transition for a wide range of temperatures and field directions. For magnetic fields parallel to the layers, the upper critical field increases approximately linearly with decreasing temperature. The upper critical field at low temperatures is...
Source: http://arxiv.org/abs/cond-mat/9904186v1
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14
Jun 28, 2018
06/18
by
J. Müller; B. Hartmann; R. Rommel; J. Brandenburg; S. M. Winter; J. A. Schlueter
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eye 14
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We have studied the low-frequency dynamics of the charge carriers in different organic charge-transfer salts $\kappa$-(BEDT-TTF)$_2$X with polymeric anions X by using resistance noise spectroscopy. Our aim is to investigate the structural, glass-like transition caused by the conformational degrees of freedom of the BEDT-TTF molecules' terminal ethylene groups. Although of fundamental importance for studies of the electronic ground-state properties, the phenomenology of the glassy dynamics is...
Topics: Strongly Correlated Electrons, Condensed Matter, Materials Science
Source: http://arxiv.org/abs/1506.05191
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75
Jul 20, 2013
07/13
by
J. Müller; M. Lang; F. Steglich; J. A. Schlueter; A. M. Kini; T. Sasaki
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We present high-resolution measurements of the coefficient of thermal expansion $\alpha (T)=\partial \ln l(T)/\partial T$ of the quasi-twodimensional (quasi-2D) salts $\kappa$-(BEDT-TTF)$_2$X with X = Cu(NCS)$_2$, Cu[N(CN)$_2$]Br and Cu[N(CN)$_2$]Cl. At intermediate temperatures (B), distinct anomalies reminiscent of second-order phase transitions have been found at $T^\ast = 38$ K and 45 K for the superconducting X = Cu(NCS)$_2$ and Cu[N(CN)$_2$]Br salts, respectively. Most interestingly, we...
Source: http://arxiv.org/abs/cond-mat/0107480v1
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49
Sep 20, 2013
09/13
by
A. -K. Klehe; T. Biggs; C. A. Kuntscher; A. M. Kini; J. A. Schlueter
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We compare magnetotransport measurements under pressure on the organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu(SCN)$_{2}$ with different pressure-media and discover that the results are pressure media dependent. This pressure-medium dependence is thought to originate from the difference in thermal contraction between the very soft and highly anisotropic sample and the isotropically contracting, but solid pressure medium, thus resulting in non-hydrostatic pressure on the sample. However,...
Source: http://arxiv.org/abs/cond-mat/0405445v2
3
3.0
Jun 30, 2018
06/18
by
A. Pustogow; E. Zhukova; B. Gorshunov; M. Pinterić; S. Tomić; J. A. Schlueter; M. Dressel
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eye 3
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The electrodynamic response of the organic spin-liquid candidate $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ has been measured in an extremely wide energy range ($10^{-13}$ to 2 eV) as a function of temperature (5 to 300 K). Below the Mott gap, excitations from the un-gapped spinon continuum cause a considerable contribution to the infrared conductivity, as suggested by the U(1) gauge theory. At THz frequencies we can identify a power-law behavior $\sigma(\omega) \propto \omega^{\beta}$ with two...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1412.4581
3
3.0
Jun 29, 2018
06/18
by
G. Koutroulakis; H. Kühne; H. H. Wang; J. A. Schlueter; J. Wosnitza; S. E. Brown
texts
eye 3
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A $^{13}$C NMR study of the normal and superconducting states of the all-organic charge-transfer salt $\beta"$-(BEDT-TTF)$_2$SF$_5$CH$_2$CF$_2$SO$_3$ is presented. We find that the normal state is a charge-ordered metal configured as vertical stripes, produced by a combination of 1/4-filling, correlations, and a polar counterion sublattice. The NMR properties associated with the superconducting state are consistent with gap nodes and singlet pairing, and therefore similar to other organic...
Topics: Condensed Matter, Strongly Correlated Electrons
Source: http://arxiv.org/abs/1601.06107
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49
Sep 22, 2013
09/13
by
S. Kaiser; M. Dressel; Y. Sun; A. Greco; J. A. Schlueter; G. L. Gard; N. Drichko
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eye 49
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We observe charge-order fluctuations in the quasi-two-dimensional organic superconductor $\beta^{\prime\prime}$-(BEDT-TTF)2 SF5 CH2 CF2 SO3 both by means of vibrational spectroscopy, locally probing the fluctuating charge order, and investigating the in-plane dynamical response by infrared reflectance spectroscopy. The decrease of effective electronic interaction in an isostructural metal suppresses both charge-order fluctuations and superconductivity, pointing on their interplay. We compare...
Source: http://arxiv.org/abs/0812.3732v2
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51
Sep 22, 2013
09/13
by
K. Cho; B. E. Smith; W. A. Coniglio; L. E. Winter; C. C. Agosta; J. A. Schlueter
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We report upper critical field measurements in the metal-free-all-organic superconductor $\beta''$-(ET)$_{2}$SF$_{5}$CH$_{2}$CF$_{2}$SO$_{3}$ obtained from measuring the in-plane penetration depth using the tunnel diode oscillator technique. For magnetic field applied parallel to the conducting planes the low temperature upper critical fields are found to exceed the Pauli limiting field calculated by using a semi-empirical method. Furthermore, we found a signature that could be the phase...
Source: http://arxiv.org/abs/0811.3647v2
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43
Sep 21, 2013
09/13
by
C. Strack; C. Akinci; B. Wolf; M. Lang; J. A. Schlueter; J. Wosnitza; D. Schweitzer; J. Mueller
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eye 43
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Resistivity measurements have been performed on a low (LR)- and high (HR)-resistance variant of the kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br superconductor. While the HR sample was synthesized following the standard procedure, the LR crystal is a result of a somewhat modified synthesis route. According to their residual resistivities and residual resistivity ratios, the LR crystal is of distinctly superior quality. He-gas pressure was used to study the effect of hydrostatic pressure on the different...
Source: http://arxiv.org/abs/cond-mat/0407478v1
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81
Sep 24, 2013
09/13
by
J. J. McGuire; T. Room; A. Pronin; T. Timusk; J. A. Schlueter; M. E. Kelly; A. M. Kini
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eye 81
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The interplane optical spectrum of the organic superconductor kappa-(BEDT-TTF)2Cu[N(CN)2]Br was investigated in the frequency range from 40 to 40,000 cm-1. The optical conductivity was obtained by Kramers-Kronig analysis of the reflectance. The absence of a Drude peak at low frequency is consistent with incoherent conductivity but in apparent contradiction to the metallic temperature dependence of the DC resistivity. We set an upper limit to the interplane transfer integral of tb = 0.1 meV. A...
Source: http://arxiv.org/abs/cond-mat/0103237v1
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55
Sep 21, 2013
09/13
by
John Singleton; P. A. Goddard; A. Ardavan; N. Harrison; S. J. Blundell; J. A. Schlueter; A. M. Kini
texts
eye 55
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Peaks in the magnetoresistivity of the layered superconductor $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$, measured in fields $\leq 45$ T applied within the layers, show that the Fermi surface is extended in the interlayer direction and enable the interlayer transfer integral ($t_{\perp} \approx 0.04$ meV) to be deduced. However, the quasiparticle scattering rate $\tau^{-1}$ is such that $\hbar/\tau \sim 6t_{\perp}$, implying that $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ meets the criterion used to identify...
Source: http://arxiv.org/abs/cond-mat/0104570v2
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64
Sep 18, 2013
09/13
by
M. Glied; S. Yasin; S. Kaiser; N. Drichko; M. Dressel; J. Wosnitza; J. A. Schlueter; G. L. Gard
texts
eye 64
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The temperature dependences of the electric-transport properties of the two-dimensional organic conductors beta"-(BEDT-TTF)2SF5CH2CF2SO3, beta"-(d8-BEDT-TTF)2SF5CH2CF2SO3, and beta"-(BEDT-TTF)2SF5CHFSO3 are measured by dc methods in and perpendicular to the highly-conducting plane. Microwave measurements are performed at 24 and 33.5 GHz to probe the high-frequency behavior from room temperature down to 2 K. Superconductivity is observed in beta"-(BEDT-TTF)2SF5CH2CF2SO3 and...
Source: http://arxiv.org/abs/0809.2202v1
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79
Sep 24, 2013
09/13
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J. Wosnitza; V. M. Gvozdikov; J. Hagel; P. J. Meeson; J. A. Schlueter; R. W. Winter; G. L. Gard
texts
eye 79
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We report on an anomalous behavior of the spin-splitting zeros in the de Haas-van Alphen (dHvA) signal of a quasi-two-dimensional organic superconductor. The zeros as well as the angular dependence of the amplitude of the second harmonic deviate remarkably from the standard Lifshitz-Kosevich (LK) prediction. In contrast, the angular dependence of the fundamental dHvA amplitude as well as the spin-splitting zeros of the Shubnikov-de Haas signal follow the LK theory. We can explain this behavior...
Source: http://arxiv.org/abs/cond-mat/0412202v1
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3.0
Jun 29, 2018
06/18
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M. Dressel; P. Lazic; A. Pustogow; E. Zhukova; B. Gorshunov; J. A. Schlueter; O. Milat; B. Gumhalter; S. Tomic
texts
eye 3
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The dimer Mott insulator $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ exhibits unusual electrodynamic properties. Numerical investigations of the electronic ground state and the molecular and lattice vibrations reveal the importance of the Cu$_2$(CN)$_3^-$ anion network coupled to the BEDT-TTF molecules: The threefold cyanide coordination of copper and linkage isomerism in the anion structure cause a loss of symmetry, frustration, disorder, and domain formation. Our findings consistently explain the...
Topics: Condensed Matter, Strongly Correlated Electrons
Source: http://arxiv.org/abs/1601.04926
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77
Sep 23, 2013
09/13
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P. A. Goddard; S. J. Blundell; J. Singleton; R. D. McDonald; A. Ardavan; A. Narduzzo; J. A. Schlueter; A. M. Kini; T. Sasaki
texts
eye 77
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The angle-dependences of the magnetoresistance of two different isotopic substitutions (deuterated and undeuterated) of the layered organic superconductor \kappa-(ET)2Cu(NCS)2 are presented. The angle dependent magnetoresistance oscillations (AMRO) arising from the quasi-one-dimensional (Q1D) and quasi-two-dimensional (Q2D) Fermi surfaces in this material are often confused. By using the Boltzman transport equation extensive simulations of the AMRO are made that reveal the subtle differences...
Source: http://arxiv.org/abs/cond-mat/0312197v1
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49
Sep 18, 2013
09/13
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M. -S. Nam; A. Ardavan; J. A. Symington; J. Singleton; N. Harrison; C. H. Mielke; J. A. Schlueter; R. W. Winter; G. L. Gard
texts
eye 49
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We show that Shubnikov-de Haas oscillations in the interlayer resistivity of the organic superconductor $\beta''$-(BEDT-TTF)$_{2}$SF$_{5}$ CH$_{2}$CF$_{2}$SO$_{3}$ become very pronounced in magnetic fields $\sim$~60~T. The conductivity minima exhibit thermally-activated behaviour that can be explained simply by the presence of a Landau gap, with the quasi-one-dimensional Fermi surface sheets contributing negligibly to the conductivity. This observation, together with complete suppression of...
Source: http://arxiv.org/abs/cond-mat/0105048v1
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53
Sep 18, 2013
09/13
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T. Lancaster; S. J. Blundell; P. J. Baker; M. L. Brooks; W. Hayes; F. L. Pratt; J. L. Manson; M. M. Conner; J. A. Schlueter
texts
eye 53
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The information accessible from a muon-spin relaxation experiment is often limited since we lack knowledge of the precise muon stopping site. We demonstrate here the possibility of localizing a spin polarized muon in a known stopping state in a molecular material containing fluorine. The muon-spin precession that results from the entangled nature of the muon-spin and surrounding nuclear spins is sensitive to the nature of the stopping site and we use this property to identify three classes of...
Source: http://arxiv.org/abs/0707.2761v1
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32
Sep 21, 2013
09/13
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L. Fang; Y. Jia; J. A. Schlueter; A. Kayani; Z. L. Xiao; H. Claus; U. Welp; A. E. Koshelev; G. W. Crabtree; W. -K. Kwok
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We report on the systematic evolution of vortex pinning behavior in isovalent doped single crystals of BaFe2(As1-xPx)2. Proceeding from optimal doped to ovedoped samples, we find a clear transfor- mation of the magnetization hysteresis from a fishtail behavior to a distinct peak effect followed by a reversible magnetization and Bean Livingston surface barriers. Strong point pinning dominates the vortex behavior at low fields whereas weak collective pinning determines the behavior at higher...
Source: http://arxiv.org/abs/1106.2599v2
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58
Sep 22, 2013
09/13
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A. F. Bangura; P. A. Goddard; J. Singleton; S. W. Tozer; A. I. Coldea; A. Ardavan; R. D. McDonald; S. J. Blundell; J. A. Schlueter
texts
eye 58
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We present experimental evidence for a hitherto unconfirmed type of angle-dependent magnetoresistance oscillation caused by magnetic breakdown. The effect was observed in the organic superconductor kappa-(BEDT-TTF)$_2$Cu(NCS)$_2$ using hydrostatic pressures of up to 9.8 kbar and magnetic fields of up to 33 T. In addition, we show that similar oscillations are revealed in ambient pressure measurements, provided that the Shubnikov-de Haas oscillations are suppressed either by elevated...
Source: http://arxiv.org/abs/cond-mat/0702570v2
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61
Sep 21, 2013
09/13
by
J. Wosnitza; J. Hagel; J. S. Qualls; J. S. Brooks; E. Balthes; D. Schweitzer; J. A. Schlueter; U. Geiser; J. Mohtasham; R. W. Winter; G. L. Gard
texts
eye 61
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The magnetic-field, temperature, and angular dependence of the interlayer magnetoresistance of two different quasi-two-dimensional (2D) organic superconductors is reported. For $\kappa$-(BEDT-TTF)$_2$I$_3$ we find a well-resolved peak in the angle-dependent magnetoresistance at $\Theta = 90^\circ$ (field parallel to the layers). This clear-cut proof for the coherent nature of the interlayer transport is absent for $\beta$''-(BEDT-TTF)$_2$SF$_5$CH$_2$CF$_2$SO$_3$. This and the non-metallic...
Source: http://arxiv.org/abs/cond-mat/0203567v1
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45
Sep 22, 2013
09/13
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K. Hashimoto; Y. Mizukami; R. Katsumata; H. Shishido; M. Yamashita; H. Ikeda; Y. Matsuda; J. A. Schlueter; J. D. Fletcher; A. Carrington; D. Gnida; D. Kaczorowski; T. Shibauchi
texts
eye 45
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When a second-order magnetic phase transition is tuned to zero temperature by a non-thermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these `quantum critical' superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature $T_c$ often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong...
Source: http://arxiv.org/abs/1302.2945v1
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43
Sep 19, 2013
09/13
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I. B. Rutel; S. A. Zvyagin; J. S. Brooks; J. Krzystek; P. Kuhns; A. P. Reyes; B. H. Ward; J. A. Schlueter; R. W. Winter; G. L. Gard
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eye 43
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A systematic electron spin resonance (ESR) investigation of the low temperature regime for the (ET)2SF5CF2SO3 system was performed in the frequency range of ~200-700 GHz, using backward wave oscillator sources, and at fields up to 25 T. Newly acquired access to the high frequency and fields shows experimental ESR results in agreement with the nuclear magnetic resonance (NMR) investigation, revealing evidence that the transition seen at 20 K is not of conventional spin-Peierls order. A...
Source: http://arxiv.org/abs/cond-mat/0209295v4
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50
Sep 22, 2013
09/13
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J. Wosnitza; S. Wanka; J. Hagel; H. v. Loehneysen; J. S. Qualls; J. S. Brooks; E. Balthes; J. A. Schlueter; U. Geiser; J. Mohtasham; R. W. Winter; G. L. Gard
texts
eye 50
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The quasi-two-dimensional organic superconductor beta-(BEDT-TTF)_2SF_5CH_2CF_2SO_3 (T_c approx 4.4 K)shows very strong Shubnikov-de Haas (SdH) oscillations which are superimposed on a highly anomalous steady background magnetoresistance, R_b. Comparison with de Haas- van Alphen oscillations allow a reliable estimate of R_b which is crucial for the correct extraction of the SdH signal. At low temperatures and high magnetic fields insulating behavior evolves. The magnetoresistance data violate...
Source: http://arxiv.org/abs/cond-mat/0011357v1
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4.0
Jun 30, 2018
06/18
by
M. Pinteric; M. Culo; O. Milat; M. Basletic; B. Korin-Hamzic; E. Tafra; A. Hamzic; T. Ivek; T. Peterseim; K. Miyagawa; K. Kanoda; J. A. Schlueter; M. Dressel; S. Tomic
texts
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We have in detail characterized the anisotropic charge response of the dimer Mott insulator $\kappa$-(BEDT-TTF)$_2$\-Cu$_2$(CN)$_3$ by dc conductivity, Hall effect and dielectric spectroscopy. At room temperature the Hall coefficient is positive and close to the value expected from stoichiometry; the temperature behavior follows the dc resistivity $\rho(T)$. Within the planes the dc conductivity is well described by variable-range hopping in two dimensions; this model, however, fails for the...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1407.6252
109
109
Jul 20, 2013
07/13
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S. Ghannadzadeh; J. S. Möller; P. A. Goddard; T. Lancaster; F. Xiao; S. J. Blundell; A. Maisuradze; R. Khasanov; J. L. Manson; S. W. Tozer; D. Graf; J. A. Schlueter
texts
eye 109
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We present the results of high-field magnetization and muon-spin relaxation measurements on the coordination polymer CuF_2(H_2O)_2(pyrazine) in pressures up to 22.5 kbar. We observe a transition from a quasi-two-dimensional to a quasi-one-dimensional antiferromagnetic phase at 9.1 kbar, driven by a rotation of the Jahn-Teller axis. Long-range antiferromagnetic ordering is seen in both regimes, as well as a phase separation in the critical pressure region. The magnetic dimensionality switching...
Source: http://arxiv.org/abs/1304.5403v1
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60
Sep 18, 2013
09/13
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P. A. Goddard; J. Singleton; P. Sengupta; R. D. McDonald; T. Lancaster; S. J. Blundell; F. L. Pratt; S. Cox; N. Harrison; J. L. Manson; H. I. Southerland; J. A. Schlueter
texts
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Pulsed-field magnetization experiments (fields $B$ of up to 85 T and temperatures $T$ down to 0.4 K) are reported on nine organic Cu-based two-dimensional (2D) Heisenberg magnets. All compounds show a low-$T$ magnetization that is concave as a function of $B$, with a sharp ``elbow'' transition to a constant value at a field $B_{\rm c}$. Monte-Carlo simulations including a finite interlayer exchange energy $J_{\perp}$ quantitatively reproduce the data; the concavity indicates the effective...
Source: http://arxiv.org/abs/0803.4169v1
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37
Sep 17, 2013
09/13
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P. A. Goddard; J. Singleton; C. Maitland; S. J. Blundell; T. Lancaster; P. J. Baker; R. D. McDonald; S. Cox; P. Sengupta; J. L. Manson; K. A. Funk; J. A. Schlueter
texts
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Although the isotope effect in superconducting materials is well-documented, changes in the magnetic properties of antiferromagnets due to isotopic substitution are seldom discussed and remain poorly understood. This is perhaps surprising given the possible link between the quasi-two-dimensional (Q2D) antiferromagnetic and superconducting phases of the layered cuprates. Here we report the experimental observation of shifts in the N\'{e}el temperature and critical magnetic fields ($\Delta T_{\rm...
Source: http://arxiv.org/abs/0807.1506v2
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54
Sep 23, 2013
09/13
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C. C. Agosta; Jing Jin; W. A. Coniglio; B. E. Smith; K. Cho; I. Stroe; C. Martin; S. W. Tozer; T. P. Murphy; E. C. Palm; J. A. Schlueter; M. Kurmoo
texts
eye 54
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We present upper critical field data for $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ with the magnetic field close to parallel and parallel to the conducting layers. We show that we can eliminate the effect of vortex dynamics in these layered materials if the layers are oriented within 0.3 degrees of parallel to the applied magnetic field. Eliminating vortex effects leaves one remaining feature in the data that corresponds to the Pauli paramagnetic limit ($H_p$). We propose a semi-empirical method to...
Source: http://arxiv.org/abs/1111.5025v3
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80
Sep 23, 2013
09/13
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S. Calder; V. O. Garlea; D. F. McMorrow; M. D. Lumsden; M. B. Stone; J. C. Lang; J. -W. Kim; J. A. Schlueter; Y. G. Shi; K. Yamaura; Y. S. Sun; Y. Tsujimoto; A. D. Christianson
texts
eye 80
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The metal-insulator transition (MIT) is one of the most dramatic manifestations of electron correlations in materials. Various mechanisms producing MITs have been extensively considered, including the Mott (electron localization via Coulomb repulsion), Anderson (localization via disorder) and Peierls (localization via distortion of a periodic 1D lattice). One additional route to a MIT proposed by Slater, in which long-range magnetic order in a three dimensional system drives the MIT, has...
Source: http://arxiv.org/abs/1202.1482v1
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63
Sep 20, 2013
09/13
by
T. Lancaster; S. J. Blundell; M. L. Brooks; P. J. Baker; F. L. Pratt; J. L. Manson; M. M. Conner; F. Xiao; C. P. Landee; F. A. Chaves; S. Soriano; M. A. Novak; T. Papageorgiou; A. Bianchi; T. Herrmannsdorfer; J. Wosnitza; J. A. Schlueter
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We present an investigation of magnetic ordering in the two-dimensional S=1/2 quantum magnet Cu(Pz)_2(ClO_4)_2 using specific heat and zero field muon-spin relaxation (\mu^+SR). The magnetic contribution to the specific heat is consistent with an exchange strength of 17.7(3) K. We find unambiguous evidence for a transition to a state of three-dimensional long range order below a critical temperature T_N=4.21(1) K using \mu^+SR even though there is no feature in the specific heat at that...
Source: http://arxiv.org/abs/cond-mat/0612317v1
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5.0
Jun 29, 2018
06/18
by
Paul A. Goddard; John Singleton; Isabel Franke; Johannes S. Moller; Tom Lancaster; Andrew J. Steele; Craig V. Topping; Stephen J. Blundell; Francis L. Pratt; C. Baines; Jesper Bendix; Ross D. McDonald; Jamie Brambleby; Martin R. Lees; Saul H. Lapidus; Peter W. Stephens; Brendan W. Twamley; Marianne M. Conner; Kylee Funk; Jordan F. Corbey; Hope E. Tran; J. A. Schlueter; Jamie L. Manson
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Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF$_2$)(pyz)$_2$]ClO$_4$ [pyz = pyrazine], [Cu$L_2$(pyz)$_2$](ClO$_4$)$_2$ [$L$ = pyO = pyridine-N-oxide and 4-phpyO = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz)$_2$]$^{2+}$ nearly square layers, but exhibit interlayer spacings that vary from 6.5713~\AA ~to 16.777~\AA, as dictated by the axial ligands. We present the structural...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter, Strongly Correlated Electrons
Source: http://arxiv.org/abs/1603.00355