The open orbits of potassium

1982 ◽  
Vol 60 (5) ◽  
pp. 687-692 ◽  
Author(s):  
A. W. Overhauser

The high-field magnetoresistance of potassium, which fails to saturate, can be an intrinsic property only if the Fermi surface is multiply connected. Direct observation of open-orbit magnetoresistance peaks by Coulter and Datars confirms this theoretical principle. Since the Brillouin zone of potassium is only half full, and the Fermi surface is nearly spherical, open orbits can occur only if the translational symmetry of the crystal is broken by a charge-density-wave structure. The open-orbit distributions that result explain the observed magnetoresistance patterns.

1982 ◽  
Vol 60 (5) ◽  
pp. 679-686 ◽  
Author(s):  
R. Fletcher

This paper provides a brief survey of the experimental and theoretical situation regarding the galvano- and thermomagnetic properties of potassium viewed within the context of the behaviour of other metals. Most of the data are consistent with various sample imperfections as being the major source of the anomalies that are found. However, the precise nature of the imperfections and the mechanism by which the imperfections produce the anomalies are not yet known. It is argued that the recently discovered detailed structure in the high field induced torque of K should be subjected to intensive experimental investigation before drawing any conclusions with regards to the possible presence of a charge density wave; the other magnetotransport properties offer little evidence either for or against such a possibility.


2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Subir Mukhopadhyay ◽  
Nishal Rai

Abstract D2-D8 model admits a numerical solution that corresponds to a charge density wave and a spin density wave. Considering that as the background, we numerically solve the Dirac equation for probe fermions. From the solution, we obtain the Green’s function and study the behaviour of the spectral density. We begin with generic fermions and have studied the formation of the Fermi surface and where it develops a gap. In addition, we have incorporated an ionic lattice and study its effect on the Fermi surface. Then we analysed the worldvolume fermions. In this particular model we do not find Fermi surface for the dual operators.


2018 ◽  
Vol 115 (27) ◽  
pp. 6986-6990 ◽  
Author(s):  
Shang Gao ◽  
Felix Flicker ◽  
Raman Sankar ◽  
He Zhao ◽  
Zheng Ren ◽  
...  

A charge density wave (CDW) is one of the fundamental instabilities of the Fermi surface occurring in a wide range of quantum materials. In dimensions higher than one, where Fermi surface nesting can play only a limited role, the selection of the particular wavevector and geometry of an emerging CDW should in principle be susceptible to controllable manipulation. In this work, we implement a simple method for straining materials compatible with low-temperature scanning tunneling microscopy/spectroscopy (STM/S), and use it to strain-engineer CDWs in 2H-NbSe2. Our STM/S measurements, combined with theory, reveal how small strain-induced changes in the electronic band structure and phonon dispersion lead to dramatic changes in the CDW ordering wavevector and geometry. Our work unveils the microscopic mechanism of a CDW formation in this system, and can serve as a general tool compatible with a range of spectroscopic techniques to engineer electronic states in any material where local strain or lattice symmetry breaking plays a role.


2021 ◽  
Vol 103 (5) ◽  
Author(s):  
M. Trigo ◽  
P. Giraldo-Gallo ◽  
J. N. Clark ◽  
M. E. Kozina ◽  
T. Henighan ◽  
...  

2021 ◽  
Author(s):  
Naotaka Yoshikawa ◽  
Hiroki Suganuma ◽  
Hideki Matsuoka ◽  
Yuki Tanaka ◽  
Pierre Hemme ◽  
...  

2021 ◽  
Vol 118 (22) ◽  
pp. 221603
Author(s):  
G. Storeck ◽  
K. Rossnagel ◽  
C. Ropers

2010 ◽  
Vol 81 (7) ◽  
Author(s):  
R. G. Moore ◽  
V. Brouet ◽  
R. He ◽  
D. H. Lu ◽  
N. Ru ◽  
...  

1993 ◽  
Vol 07 (23n24) ◽  
pp. 3973-4003 ◽  
Author(s):  
P. FOURY ◽  
J.P. POUGET

The structural instabilities towards the formation of a charge density wave (CDW) ground state exhibited by several layered Mo and W bronzes and oxides are reviewed. It is shown that in these two-dimensional (2D) metals, including the purple bronzes A x Mo 6 O 17 (A=K, Na, Tl; x≈1), the γ and η phases of MO 4 O 11 and the monophosphate tungsten bronzes with pentagonal tunnels ( PO 2)4 ( WO 3)2m(m=4, 6, 7), the CDW instability can be associated with particular chains of MoO 6 or WO 6 octahedra of the ReO 3 type slabs along which there is a strong overlap of the t 2g orbitals. The CDW critical wave vectors of the purple bronzes, Mo 4 O 11 and the tungsten bronzes with m=4 and 6 lead to a common nesting between differently oriented 1D Fermi surfaces. It is suggested that the anharmonic CDW modulation, which occurs in the tungsten bronzes with m≥7, could be the structural fingerprint of electron localization effects.


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