Seebeck effect studies in the charge density wave state of organic conductor α −(BEDT −TTF)2KHg(SCN)4

2021 ◽  
Author(s):  
Danica Krstovska ◽  
Eun Sang Choi ◽  
Eden Steven
Keyword(s):  
Magnetic Field ◽  
Fermi Surface ◽  
Temperature Dependence ◽  
Density Wave ◽  
Transport Processes ◽  
Seebeck Effect ◽  
Complex Nature ◽  
Organic Conductor ◽  
Background Magnetic Field ◽  
Wide Range

Abstract Angular, magnetic field and temperature dependence of the interlayer Seebeck effect of the multiband organic conductor α −(BEDT −TTF)2KHg(SCN)4 is experimentally studied at temperatures down to 0.55 K and fields up to 31 T in a wide range of angles. The background magnetic field and angular component of the Seebeck effect as well as the magnetic quantum oscillations that originate from the closed Fermi surface orbits are analyzed. The background interlayer Seebeck effect components show that above certain tilt angle of the magnetic field and above the kink field there is another CDW state in α −(BEDT −TTF)2KHg(SCN)4, between previously known CDW0 and CDWx states, in agreement with magnetoresistance and magnetization studies in this material. Our observations show that this state possesses some of the properties of the CDW0 state. The Fermi surface in the third CDW state is still reconstructed but less imperfectly nested as expected as this state develops above the kink field. The temperature dependence of the interlayer Seebeck effect reveals that this state is developed at temperatures below 3 K and at field orientations around the second AMRO maximum. In addition, for the first time, a detailed T−θ phase diagram of α − (BEDT − TTF)2KHg(SCN)4 based purely on Seebeck effect measurements is presented. We find that other states and transitions, beside the CDW states, also exist in a given temperature and angular range that have not been previously reported. These observations change the whole picture about the transport processes in the organic conductor α −(BEDT −TTF)2KHg(SCN)4 and allow to better understand the complex nature of the CDW order in this and similar compounds.

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.

Interplay of the spin-density-wave state and magnetic field in the organic conductor α-(BEDT-TTF)2KHg(SCN)4

1996 ◽  
Vol 54 (18) ◽  
pp. 12969-12978 ◽  
Author(s):  
Takahiko Sasaki ◽  
Andrei G. Lebed ◽  
Tetsuo Fukase ◽  
Naoki Toyota
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Organic Conductor ◽  
Wave State

MAGNETIC FIELD-INDUCED DENSITY WAVE TRANSITION IN A τ-PHASE ORGANIC CONDUCTOR

2002 ◽  
Author(s):  
D. GRAF ◽  
L. BALICAS ◽  
J. S. BROOKS ◽  
C. MIELKE ◽  
G. C. PAPAVASSILIOU
Keyword(s):  
Magnetic Field ◽  
Density Wave ◽  
Organic Conductor

CHARGE DENSITY WAVE INSTABILITY IN TlMo6O17

2000 ◽  
Vol 14 (10) ◽  
pp. 345-354 ◽  
Author(s):  
RUI XIONG ◽  
QINGMING XIAO ◽  
JING SHI ◽  
HAILIN LIU ◽  
WUFENG TANG ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Fermi Surface ◽  
Charge Density ◽  
Temperature Dependence ◽  
Thermoelectric Power ◽  
Charge Density Wave ◽  
Density Wave ◽  
Two Dimensional ◽  
Wave Instability ◽  
Partial Opening

The charge density wave instability in the quasi-two-dimensional conductor thallium purple molybdenum bronze TlMo 6 O 17 was carefully examined by studying the temperature dependence of resistivity, thermoelectric power (TEP) behavior and magnetic susceptibility. A metal-to-metal transition was confirmed near 110 K in TlMo 6 O 17 due to the partial opening of a gap at the Fermi surface and the driving of charge density wave.

scholarly journals Electron-momentum dependence of electron-phonon coupling underlies dramatic phonon renormalization in YNi2B2C

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Philipp Kurzhals ◽  
Geoffroy Kremer ◽  
Thomas Jaouen ◽  
Christopher W. Nicholson ◽  
Rolf Heid ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Inelastic Neutron Scattering ◽  
Density Wave ◽  
Momentum Dependence ◽  
Phonon Coupling ◽  
Electronic Band ◽  
Electron Momentum ◽  
Electron Phonon Coupling ◽  
Wide Range ◽  
Fermi Surface Nesting

AbstractElectron-phonon coupling, i.e., the scattering of lattice vibrations by electrons and vice versa, is ubiquitous in solids and can lead to emergent ground states such as superconductivity and charge-density wave order. A broad spectral phonon line shape is often interpreted as a marker of strong electron-phonon coupling associated with Fermi surface nesting, i.e., parallel sections of the Fermi surface connected by the phonon momentum. Alternatively broad phonons are known to arise from strong atomic lattice anharmonicity. Here, we show that strong phonon broadening can occur in the absence of both Fermi surface nesting and lattice anharmonicity, if electron-phonon coupling is strongly enhanced for specific values of electron-momentum, k. We use inelastic neutron scattering, soft x-ray angle-resolved photoemission spectroscopy measurements and ab-initio lattice dynamical and electronic band structure calculations to demonstrate this scenario in the highly anisotropic tetragonal electron-phonon superconductor YNi2B2C. This new scenario likely applies to a wide range of compounds.

The HelCat basic plasma science device

2014 ◽  
Vol 81 (1) ◽  
Author(s):  
M. Gilmore ◽  
A. G. Lynn ◽  
T. R. Desjardins ◽  
Y. Zhang ◽  
C. Watts ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Medium Size ◽  
Plasma Parameters ◽  
Plasma Sources ◽  
Plasma Gun ◽  
Background Magnetic Field ◽  
Wide Range ◽  
Plasma Science ◽  
Helicon Source

TheHelicon-Cathode(HelCat) device is a medium-size linear experiment suitable for a wide range of basic plasma science experiments in areas such as electrostatic turbulence and transport, magnetic relaxation, and high power microwave (HPM)-plasma interactions. The HelCat device is based on dual plasma sources located at opposite ends of the 4 m long vacuum chamber – an RF helicon source at one end and a thermionic cathode at the other. Thirteen coils provide an axial magnetic fieldB⩾ 0.220 T that can be configured individually to give various magnetic configurations (e.g. solenoid, mirror, cusp). Additional plasma sources, such as a compact coaxial plasma gun, are also utilized in some experiments, and can be located either along the chamber for perpendicular (to the background magnetic field) plasma injection, or at one of the ends for parallel injection. Using the multiple plasma sources, a wide range of plasma parameters can be obtained. Here, the HelCat device is described in detail and some examples of results from previous and ongoing experiments are given. Additionally, examples of planned experiments and device modifications are also discussed.

Investigation of the elastic properties of UNI2Si2 as a function of temperature, magnetic field, and pressure

2003 ◽  
Vol 81 (6) ◽  
pp. 797-804 ◽  
Author(s):  
G Quirion ◽  
A Kelly ◽  
S Newbury ◽  
F S Razavi ◽  
J D Garrett
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Temperature Dependence ◽  
Elastic Properties ◽  
Magnetic Phase ◽  
Density Wave ◽  
Spin Density Wave ◽  
Magnetic Phase Diagram ◽  
75.40 Cx ◽  
62.20 Dc

It is now well-established that the strong anisotropy in the magnetic properties of the intermetallic compounds UT2Si2, where T stands for a transition metal, is responsible for their rich magnetic phase diagram. However, within that series of compounds, UNi2Si2 is one that shows an unusual sequence of magnetically ordered states. Thus, to better understand its unusual properties, we have investigated the elastic properties of UNi2Si2 as a function of temperature, magnetic field, and pressure. In all three magnetic phases, our measurements indicate that the sound-velocity temperature dependence is dominated by the magnetoelastic coupling. Moreover, the analysis of the temperature dependence for the incommensurate longitudinal spin-density wave phase is consistent with a critical exponent β = 0.38 ± 0.01. We also present the magnetic phase diagram for UNi2Si2 obtained at 0 and 8 kbar. Our investigation reveals that the triple-point coordinates (Tp, Hp) decrease with pressure at a rate of dTp/dP = –0.1 K/kbar and dHp/dP = –0.1 T/kbar, respectively. PACS Nos.: 75.30.kz, 62.20.Dc, 62.50.+p, 75.40.Cx

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