Damping of field-induced chemical potential oscillations in ideal two-band compensated metals

Fortin, Jean-Yves; Audouard, Alain

doi:10.1103/physrevb.77.134440

Cited by 13 publications

(24 citation statements)

References 25 publications

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“…The minimal periodicity T E of the spectrum is, in this case and for a given phase , equal to T E =2bp 0 / m e ‫ء‬ , which is twice the periodicity calculated for an isolated system made of one hole and one electron band. 21 The number of solutions inside each interval of width T E is found to be equal to 2͑p 0 + q 0 ͒ ͑this number is conserved when p varies and can be counted exactly for p =0͒. Given a set of solutions E eh ͑q , n , ͒, n =0,¯,2͑p 0 + q 0 ͒ − 1, we introduce a cutoff function c ͑E͒ such as c ͑E͒ = 1 for E larger than a characteristic energy E c and equal to exp͓−c͑E − E c ͒ 2␦ ͔ for E Յ E c , where ␦ is any positive integer greater than 1 ͑we take ␦ = 4 in the simulations which gives a very smooth cutoff function͒, and c a positive parameter determined self-consistently.…”

Section: Modelmentioning

confidence: 97%

“…15,16 Contrary to the above-mentioned examples, the Fermi surface of numerous organic metals is composed of compensated electron-and hole-type closed orbits, 17 yielding many frequency combinations as well, as far as Shubnikov-de Haas oscillations are concerned. [18][19][20] In the case of a Fermi surface composed of two compensated orbits coupled to each other through magnetic breakdown but isolated from the other orbits outside the first Brillouin zone, it has been shown that the oscillations of the chemical potential can be strongly damped 21 which could account for the absence of frequency combinations reported in the de Haas-van Alphen ͑dHvA͒ spectra of two-dimensional ͑2D͒ networks of compensated orbits in fields up to 28 T. 20 However, the Fermi surface considered in Ref. 21 which, to our knowledge, has no counterpart among the compounds synthesized up to now, does not provide a network of orbits and, therefore, do not yield Landau bands in magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Random walks and magnetic oscillations in compensated metals

Fortin

Audouard

2009

Phys. Rev. B

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The field- and temperature-dependent de Haas-van Alphen oscillations spectrum is studied for an ideal two-dimensional compensated metal whose Fermi surface is made of a linear chain of successive orbits with electron and hole character, coupled by magnetic breakdown. We show that the first harmonics amplitude can be accurately evaluated on the basis of the Lifshits-Kosevich (LK) formula by considering a set of random walks on the orbit network, in agreement with the numerical resolution of semi-classical equations. Oppositely, the second harmonics amplitude does not follow the LK behavior and vanishes at a critical value of the field-to-temperature ratio which depends explicitly on the relative value between the hole and electron effective masses.Comment: 9 pages, 10 figures. Submitted to Physical Review

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Section: Modelmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Random walks and magnetic oscillations in compensated metals

Fortin

Audouard

2009

Phys. Rev. B

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“…Recently, we have studied the de Haas van Alphen (dHvA) oscillation 15 in the tight-binding model for (TMTSF) 2 NO 3 where electron and hole pockets coexist [27][28][29] . In that system the dHvA oscillation has been usually studied in the phenomenological theory of magnetic breakdown 30,31 and the Lifshitz and Kosevich (LK) formula 32,33 . The dHvA oscillation and the LK formula [34][35][36][37] are explained in Appendix B.…”

Section: Introductionmentioning

confidence: 99%

Three-quarter Dirac points, Landau levels, and magnetization in α−(BEDT−TTF)2I3

Kishigi

Hasegawa

2017

Phys. Rev. B

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The energies as a function of the magnetic field (H) and the pressure are studied theoretically in the tight-binding model for the two-dimensional organic conductor, α-(BEDT-TTF)2I3, in which massless Dirac fermions are realized. The effects of the uniaxial pressure (P ) are studied by using the pressure-dependent hopping parameters. The system is semi-metallic with the same area of an electron pocket and a hole pocket at P < 3.0 kbar, where the energies (ε 0 D ) at the Dirac points locate below the Fermi energy (ε 0 F ) when H = 0. We find that at P = 2.3 kbar the Dirac cones are critically tilted. In that case a new type of band crossing occurs at "three-quarter"-Dirac points, i.e., the dispersion is quadratic in one direction and linear in the other three directions. We obtain new magnetic-field-dependences of the Landau levels (εn); εn − ε 0 D ∝ (nH)4/5 at P = 2.3 kbar ("three-quarter"-Dirac points) and |εn − ε 0 F | ∝ (nH) 2 at P = 3.0 kbar (the critical pressure for the semi-metallic state). We also study the magnetization as a function of the inverse magnetic field. We obtain two types of quantum oscillations. One is the usual de Haas van Alphen (dHvA) oscillation, and the other is the unusual dHvA-like oscillation which is seen even in the system without the Fermi surface.

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“…The tunnel probability (10) evaluates for our model parameters to TðEÞ ¼ exp½−0.52NðE=tÞ 2 . The contribution of an orbit to the Fourier amplitude contains a factor t ¼ ffiffiffi ffi T p for each transmission through the Weyl point and a factor r ¼ ffiffiffiffiffiffiffiffiffiffiffi 1 − T p for each reflection [40]. In Fig.…”

Section: -2mentioning

confidence: 99%

Magnetic Breakdown and Klein Tunneling in a Type-II Weyl Semimetal

2016

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The band structure of a type-II Weyl semimetal has pairs of electron and hole pockets that coexist over a range of energies and touch at a topologically protected conical point. We identify signatures of this Weyl point in the magnetic quantum oscillations of the density of states, observable in thermodynamic properties. Tunneling between the electron and hole pockets in a magnetic field is the momentum space counterpart of Klein tunneling at a p-n junction in real space. This magnetic breakdown happens at a characteristic field strength that vanishes when the Fermi level approaches the Weyl point. The topological distinction between connected and disconnected pairs of type-II Weyl cones can be distinguished by the qualitatively different dependence of the quantum oscillations on the direction of the magnetic field. DOI: 10.1103/PhysRevLett.116.236401 Weyl semimetals provide a condensed matter realization of massless relativistic fermions [1]. Their spectrum features a diabolo-shaped surface in energy-momentum space that separates helical electronlike states (moving in the direction of the momentum) from holelike states (moving opposite to the momentum) [2]. These "Weyl cones" are the three-dimensional analogue of the two-dimensional Dirac cones in graphene. The third spatial dimension provides a topological protection, by which the conical point (Weyl point) cannot be opened up unless two Weyl cones of opposite helicity are brought together in momentum space [3].Although the Weyl point cannot be locally removed, the cones can be tilted and may even tip over [4][5][6][7][8][9][10][11][12]. For the relativistic Weyl cone such a distortion is forbidden by particle-hole symmetry, but that is not a fundamental symmetry in condensed matter. While in graphene the high symmetry of the honeycomb lattice keeps the cone upright, strain providing only a weak tilt [13], the tilting can be strong in 3D Weyl semimetals. This leads to a natural division of Weyl cones into two topologically distinct types [9]. In type I the cone is only weakly tilted so that the electronlike states and holelike states occupy separate energy ranges, above or below the Weyl point. In type II the cone has tipped over so that electron and hole states coexist in energy. Many experimental realizations of a type-II Weyl semimetal have recently been reported [14][15][16][17][18][19][20][21].In a magnetic field the coexisting electron and hole pockets of a type-II Weyl semimetal are coupled by tunneling through the Weyl point (Fig. 1). Here we investigate how this process, a momentum space manifestation of Klein tunneling [22], affects the magnetic quantum oscillations of the density of states (de Haas-van Alphen effect), providing a unique thermodynamic signature of the topologically protected band structure (an alternative to proposed transport signatures [9,[23][24][25]). Because the quantum oscillations are governed by extremal cross sections of the Fermi surface, one might wonder whether some symmetry is required to align the extremal cross sect...

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Damping of field-induced chemical potential oscillations in ideal two-band compensated metals

Cited by 13 publications

References 25 publications

Random walks and magnetic oscillations in compensated metals

Random walks and magnetic oscillations in compensated metals

Three-quarter Dirac points, Landau levels, and magnetization in α−(BEDT−TTF)2I3

Magnetic Breakdown and Klein Tunneling in a Type-II Weyl Semimetal

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