共查询到20条相似文献,搜索用时 15 毫秒
1.
Jung Sang You Inho Lee E.S. Choi Y.J. Jo J.H. Shim Jun Sung Kim 《Current Applied Physics》2019,19(3):230-235
We investigate the physical properties of massive Dirac fermions in SrMnSb2 using transport, specific heat, electronic structure calculations, and Shubnikov-de Haas (SdH) oscillations. SrMnSb2 is a candidate Dirac antiferromagnet, consisting of the MnSb layers and the distorted square net of Sb atoms with a zigzag chain structure. This structural distortion leads to gap opening at the band crossing point found in the square lattice of the sister compound SrMnBi2 but leaves another Dirac band crossing near the Brillouin zone boundary. The small 2D Fermi surface with a light electron mass and a small Fermi energy is confirmed by the large resistivity anisotropy, the large Seebeck coefficient, and also the angle and temperature dependent SdH oscillations. The Berry phase obtained from the SdH oscillations is trivial, in contrast to the case of SrMnBi2. The relatively large spin orbit coupling gap and the small Fermi energy in SrMnSb2 is found to be essential to understand this contrasting behavior of the massive Dirac fermions as compared to SrMnBi2. Our observations demonstrate that the Berry phase of the mobile electrons in SrMnSb2 is sensitive to the Fermi level change and can be tuned by doping or deficiency. 相似文献
2.
P. Monceau 《Solid State Communications》1977,24(4):331-334
We have measured the resistivity of the linear transition metal trichalco-genide NbSe3 in magnetic fields up to 180 kG. We observe large Shubnikov-de Haas oscillations. The measurements reveal a strong anisotropy in the a.c. plane perpendicular to the chain direction. A ratio of 3 in the cyclotron effective masses for the two orthogonal directions in this plane is determined. Spin splitting occurs for high magnetic field, and we obtain a Landé factor g of 2.45. 相似文献
3.
4.
Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ρ(xy) is nonlinear at low magnetic fields. ρ(xy) is fitted assuming multiple carrier contributions. We infer the density of the mobile charge carriers from the oscillations frequency and from Hall measurements. The comparison between these densities suggests multiple valley and spin degeneracy. The small amplitude of the oscillation is discussed in the framework of the multiple band scenario. 相似文献
5.
Surface Shubnikov-de Haas oscillations have been measured in p-type channels of (110) silicon field effect transitors between 1.4 and 4.2 K in magnetic fields up to 10 Tesla. Two electric subbands were revealed and the effective masses of the holes in both bands could be determined. For one subband the dependence of the mass on the surface electric field was investigated. At low gate voltages the g-factor of the holes was measured from the spin splitting of the Landau-levels. 相似文献
6.
《Superlattices and Microstructures》1995,18(1):67-73
We have studied negative magnetoresistance due to the weak localization effects in a 2D electron gas (2DEG) grown on dimpled substrates. Since the 2DEG is sensitive only to the normal component of B, depending on the orientation of the external magnetic field, electrons will move in a spatially inhomogeneous (B perpendicular to the substrate-B⊥) or sign alternating, random magnetic field (B parallel to the substrate B∥). A difference in the magnetoresistance at B∥ and B⊥ is seen for the sample with a coherence length larger than the spatial periodicity of magnetic field. We believe that the difference in the magnetic flux through the closed electron trajectories at B∥ and B⊥, taken into account random character of B∥, is responsible for this behaviour. Features connected with Aharonov Bohm flux through the different areas on the dimpled surface were observed. 相似文献
7.
Recent measurements of a 2D electron gas subjected to microwave radiation reveal a magnetoresistance with an oscillatory dependence on the ratio of radiation frequency to cyclotron frequency. We perform a diagrammatic calculation and find radiation-induced resistivity oscillations with the correct period and phase. Results are explained via a simple picture of current induced by photoexcited disorder-scattered electrons. The oscillations increase with radiation intensity, easily exceeding the dark resistivity and resulting in negative-resistivity minima. At high intensity, we identify additional features, likely due to multiphoton processes, which have yet to be observed experimentally. 相似文献
8.
9.
Experimental and theoretical evidence is presented for new low-magnetic-field (B<5 kG) 1/B oscillations in the thermoelectric power of a high-mobility GaAs/AlGaAs two-dimensional (2D) electron gas. The oscillations result from inter-Landau-level resonances of acoustic phonons carrying a momentum equal to twice the Fermi wave number at B=0. Numerical calculations show that both 3D and 2D phonons can contribute to this effect. 相似文献
10.
Z. D. Kvon D. A. Kozlov S. N. Danilov C. Zoth P. Vierling S. Stachel V. V. Bel’kov A. K. Bakarov D. V. Dmitriev A. I. Toropov S. D. Ganichev 《JETP Letters》2013,97(1):41-44
The terahertz response of a high-density and high-mobility two-dimensional electron gas in 13-nm GaAs quantum wells at frequencies of 0.7 and 1.63 THz has been investigated. Terahertz radiation-induced magnetoresistance oscillations have been discovered. The oscillation maxima coincide with the harmonics of cyclotron resonance. It has been shown that a large number of harmonics (up to the ninth) appear under irradiation at a frequency of 0.7 THz. In this case, the effect is the analogue of microwave-induced oscillations. At a higher frequency, the oscillation amplitude decreases drastically with an increase in the harmonic number. This indicates a transition to the regime of ordinary cyclotron harmonics. 相似文献
11.
S. A. Tarasenko 《Physics of the Solid State》2002,44(9):1769-1773
A theory of the Shubnikov-de Haas effect is developed for two-dimensional systems in a tilted magnetic field. The conductivity tensor is calculated for an arbitrary ratio r of the Zeeman splitting to the cyclotron splitting. Possible anisotropy of the g factor is taken into account. It is shown that at integer values of r, the main harmonic dominates in the spectrum of Shubnikov-de Haas oscillations and the phase of the oscillations depends on the parity of r. At half-integer values of r, the conductivity oscillations are determined by the harmonics of the second order of smallness. 相似文献
12.
Dyke P Kuhnle ED Whitlock S Hu H Mark M Hoinka S Lingham M Hannaford P Vale CJ 《Physical review letters》2011,106(10):105304
We have studied the transition from two to three dimensions in a low temperature weakly interacting 6Li Fermi gas. Below a critical atom number N(2D) only the lowest transverse vibrational state of a highly anisotropic oblate trapping potential is occupied and the gas is two dimensional. Above N(2D) the Fermi gas enters the quasi-2D regime where shell structure associated with the filling of individual transverse oscillator states is apparent. This dimensional crossover is demonstrated through measurements of the cloud size and aspect ratio versus atom number. 相似文献
13.
S. I. Dorozhkin M. O. Skvortsova A. V. Kudrin B. N. Zvonkov Yu. A. Danilov O. V. Vikhrova 《JETP Letters》2010,91(6):292-296
The magnetoresistance of an InGaAs/GaAs heterostructure with a two-dimensional hole channel has been measured in quantizing
magnetic fields. Beatings of Shubnikov-de Haas oscillations have been observed, which indicate that the spin degeneracy of
the system is lifted owing to the spin-orbit interaction. The oscillation pattern is independent of the magnetic field component
parallel to the two-dimensional system; this independence is characteristic of size-quantization heavy-hole subbands. 相似文献
14.
15.
16.
We have performed electrical transport measurements at low temperatures and high magnetic fields in Na(0.5)CoO2 single crystals. Shubnikov-de Haas oscillations corresponding to only 1% of the area of the orthorhombic Brillouin zone were clearly observed, indicating that most of the original Fermi surface vanishes at the charge-ordering (CO) transition. In-plane magnetic fields were found to suppress strongly the CO state. For fields rotated within the conducting planes, we observe angular magnetoresistance oscillations whose periodicity changes from twofold to sixfold at the transition. 相似文献
17.
R.J. Nicholas R.A. Stradling J.C. Portal P. Perrier S. Askenazy 《Solid State Communications》1979,31(6):437-441
Shubnikov-de Haas oscillations have been studied in n-channel silicon 〈100〉 MOSFETS in magnetic fields up to 35 T. At high magnetic fields the shape of the conductivity peaks becomes asymmetric and the conductivity from whole regions of the Landau level spectrum is suppressed by the magnetic field. The asymmetry is thought to arise from the low effective density of scatterers which occurs for high magnetic fields, as predicted by Ando. These effects may also be related to the presence of phenomena such as Wigner crystallisation or Anderson localisation. 相似文献
18.
A study is made of the effect of uniaxial mechanical stress on Shubnikov-de Haas oscillations in two-dimensional hole channels
of silicon field-effect transistors. It is shown that the main effect of the stress is a shift of the node of the beats of
the oscillations. This shift corresponds in the case of compression (tension) to an increase (decrease) of the spin splitting
in a zero magnetic field. In the case of two filled size-quantization subbands a mechanical stress of either sign causes a
small fraction of the carriers to be transferred from the lower into the upper subband.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 9, 630–635 (10 November 1996) 相似文献
19.
Liu M Zhang J Chang CZ Zhang Z Feng X Li K He K Wang LL Chen X Dai X Fang Z Xue QK Ma X Wang Y 《Physical review letters》2012,108(3):036805
We report transport studies on magnetically doped Bi(2)Se(3) topological insulator ultrathin films grown by molecular beam epitaxy. The magnetotransport behavior exhibits a systematic crossover between weak antilocalization and weak localization with the change of magnetic impurity concentration, temperature, and magnetic field. We show that the localization property is closely related to the magnetization of the sample, and the complex crossover is due to the transformation of Bi(2)Se(3) from a topological insulator to a topologically trivial dilute magnetic semiconductor driven by magnetic impurities. This work demonstrates an effective way to manipulate the quantum transport properties of the topological insulators by breaking time-reversal symmetry. 相似文献
20.
《Physics letters. A》1986,113(7):381-383
High pressure electrical resistance experiments performed on a single crystal of CeAl2 allow one to determine a characteristic line in the pressure-temperature plane where a continuous passage from weak to strong Kondo behaviour is observed. This line is not associated with any sizeable volume anomaly as shown by X-ray experiments. 相似文献