Low Temperature Magnetotransport Properties of Polycrystalline Ca3Co4O9

MRS Advances ◽  
2017 ◽  
Vol 2 (23) ◽  
pp. 1237-1242
Author(s):  
David J. Magginetti ◽  
Shrikant Saini ◽  
Ashutosh Tiwari
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Band Structure ◽  
Density Wave ◽  
Spin Density Wave ◽  
Significant Component ◽  
Resistivity Measurements ◽  
Metal To Insulator Transition ◽  
Conventional Behavior ◽  
Physical Features

ABSTRACTCa3Co4O9 (CCO) is a promising material for thermoelectric applications; however, this layered oxide shows a large number of physical features that complicate understanding and systematically improving its properties. A significant component of CCO’s behavior is its magnetotransport properties, particularly in the low temperature region where an incommensurate spin density wave affects its band structure. In order to improve understanding in this area, we perform low temperature magnetoresistance (MR) measurements on a bulk CCO sample. Field-less resistivity measurements confirm the conventional behavior of our sample, with a metal-to-insulator transition at approximately 70 K, and a shoulder indicating ferrimagnetism at 14 K. Resistivity vs. temperature under applied magnetic field show significant MR below around 35 K.

scholarly journals Linear magnetoresistance in the low-field limit in density-wave materials

2019 ◽  
Vol 116 (23) ◽  
pp. 11201-11206 ◽  
Author(s):  
Yejun Feng ◽  
Yishu Wang ◽  
D. M. Silevitch ◽  
J.-Q. Yan ◽  
Riki Kobayashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Applied Field ◽  
Density Wave ◽  
Spin Density Wave ◽  
Field Limit ◽  
Fermi Surfaces ◽  
Low Field ◽  
Metallic Charge ◽  
Linear Magnetoresistance

The magnetoresistance (MR) of a material is typically insensitive to reversing the applied field direction and varies quadratically with magnetic field in the low-field limit. Quantum effects, unusual topological band structures, and inhomogeneities that lead to wandering current paths can induce a cross-over from quadratic to linear MR with increasing magnetic field. Here we explore a series of metallic charge- and spin-density-wave systems that exhibit extremely large positive linear MR. By contrast to other linear MR mechanisms, this effect remains robust down to miniscule magnetic fields of tens of Oersted at low temperature. We frame an explanation of this phenomenon in a semiclassical narrative for a broad category of materials with partially gapped Fermi surfaces due to density waves.

NOVEL VORTEX STRIPE PHASE UNDER STRONG MAGNETIC FIELD IN HIGH TEMPERATURE SUPERCONDUCTORS

2005 ◽  
Vol 19 (01n03) ◽  
pp. 9-12 ◽  
Author(s):  
YAN CHEN ◽  
Z. D. WANG ◽  
C. S. TING
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Low Temperature ◽  
Vortex Structure ◽  
High Temperature Superconductors ◽  
Density Wave ◽  
Spin Density Wave ◽  
Upper Critical Field ◽  
Stripe Phase ◽  
Stripe Phases

The nature of vortex structure in the mixed state of high-temperature superconductors (HTS) is investigated by solving the Bogoliubov-de Gennes equations with consideration of competition between antiferromagnetic (AF) and d-wave superconductivity (DSC) orders. By varying the applied magnetic field and temperature, the geometry of vortex structure can take two different forms: conventional vortex lattice (triangular or square), or vortex stripe phases where all the order parameters including spin density wave, charge density wave and superconducting order exhibit stripe-like behavior. This novel vortex stripe phases may show up at low temperature and adjacent to upper critical field H c2 Phase diagram of temperature dependence of H c2 will be presented. Our results may shed light on the understanding of the low-temperature H c2 anomalies in some HTS. New experiments are proposed to test our predictions.

Strong sensitivity to magnetic field of the low-temperature heat capacity of (TMTSF)2PF6

2002 ◽  
Vol 12 (9) ◽  
pp. 27-29
Author(s):  
J. C. Lasjaunias ◽  
S. Sahling ◽  
K. Biljakovic ◽  
P. Monceau
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Ground State ◽  
Crystal Orientation ◽  
Density Wave ◽  
Spin Density Wave ◽  
Temperature Heat ◽  
Low Temperature Heat Capacity ◽  
Low Temperature Specific Heat ◽  
Low Magnetic Field

We have observed a very large sensitivity to low magnetic field (i.e. below 0.5 Tesla) of the low-temperature specific heat Cp of the quasi-1D compound (TMTSF)2PF6 in its spin-density wave (SDW) ground state. This effect is independent on the field direction compared to that of the crystal orientation (with H || either to $\bf a$ or $\bf b'$ axis), and hence does not seem to be related in a direct way to the electronic SDW itself. In addition, we did not detect any feature in Cp at the spin-flop transition (at $H=0.45$ T, || $\bf b'$ axis).

scholarly journals Old Donors for New Molecular Conductors: Combining TMTSF and BEDT-TTF with Anionic (TaF6)1−x/(PF6)x Alloys

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 386
Author(s):  
Magali Allain ◽  
Cécile Mézière ◽  
Pascale Auban-Senzier ◽  
Narcis Avarvari
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Density Wave ◽  
Spin Density Wave ◽  
Orthorhombic Phase ◽  
Molecular Conductors ◽  
Bechgaard Salts ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Resistivity Measurements

Tetramethyl-tetraselenafulvalene (TMTSF) and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) are flagship precursors in the field of molecular (super)conductors. The electrocrystallization of these donors in the presence of (n-Bu4N)TaF6 or mixtures of (n-Bu4N)TaF6 and (n-Bu4N)PF6 provided Bechgaard salts formulated as (TMTSF)2(TaF6)0.84(PF6)0.16, (TMTSF)2(TaF6)0.56(PF6)0.44, (TMTSF)2(TaF6)0.44(PF6)0.56 and (TMTSF)2(TaF6)0.12(PF6)0.88, together with the monoclinic and orthorhombic phases δm-(BEDT-TTF)2(TaF6)0.94(PF6)0.06 and δo-(BEDT-TTF)2(TaF6)0.43(PF6)0.57, respectively. The use of BEDT-TTF and a mixture of (n-Bu4N)TaF6/TaF5 afforded the 1:1 phase (BEDT-TTF)2(TaF6)2·CH2Cl2. The precise Ta/P ratio in the alloys has been determined by an accurate single crystal X-ray data analysis and was corroborated with solution 19F NMR measurements. In the previously unknown crystalline phase (BEDT-TTF)2(TaF6)2·CH2Cl2 the donors organize in dimers interacting laterally yet no organic-inorganic segregation is observed. Single crystal resistivity measurements on the TMTSF based materials show typical behavior of the Bechgaard phases with room temperature conductivity σ ≈ 100 S/cm and localization below 12 K indicative of a spin density wave transition. The orthorhombic phase δo-(BEDT-TTF)2(TaF6)0.43(PF6)0.57 is semiconducting with the room temperature conductivity estimated to be σ ≈ 0.16–0.5 S/cm while the compound (BEDT-TTF)2(TaF6)2·CH2Cl2 is also a semiconductor, yet with a much lower room temperature conductivity value of 0.001 to 0.0025 S/cm, in agreement with the +1 oxidation state and strong dimerization of the donors.

Magnetic-field behavior of the spin-density-wave state in (TMTSF)2AsF6

1995 ◽  
Vol 52 (22) ◽  
pp. 15983-15991 ◽  
Author(s):  
J. L. Musfeldt ◽  
M. Poirier ◽  
P. Batail ◽  
C. Lenoir
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Wave State ◽  
Field Behavior

COLLECTIVE FIELD THEORY TO MAGNETIC-FIELD-INDUCED SPIN-DENSITY-WAVE-STATE IN BECHGAARD SALTS, (TMTSF)2X

1993 ◽  
Vol 07 (19) ◽  
pp. 3415-3421 ◽  
Author(s):  
ALEXANDRE S. ROZHAVSKY
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Chemical Potential ◽  
Density Wave ◽  
Spin Density Wave ◽  
Hall Conductivity ◽  
Chiral Anomaly ◽  
Threshold Field ◽  
Wave State ◽  
Extended States

A field description of spin-density-wave (SDW) in a quasi-two-dimensional metal with open Fermi surface in magnetic field, is proposed. The SDW transition temperature, T c (H), and the Hall conductivity σxy, are calculated. The dependence T c (H) is found to be different from that of the Bardeen-Cooper-Schrieffer model, in particular, a threshold field, H c , found its natural explanation. It is proved that the quantized Hall conductivity arises from the chiral anomaly terms in the effective action provided there is pinning of chemical potential in the gap of extended states.

High magnetic field NMR investigation of the spin density wave phase of TMTSF2PF6

2002 ◽  
Vol 12 (9) ◽  
pp. 389-389
Author(s):  
W. G. Clark ◽  
F. Zamborsky ◽  
B. Alavi ◽  
P. Vonlanthen ◽  
W. Moulton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Proton Relaxation ◽  
High Magnetic Fields ◽  
Organic Conductor ◽  
First Order ◽  
The Magnetic Field ◽  
Very High

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.

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