Prominent metallic surface conduction and the singular magnetic response of topological Dirac fermion in three-dimensional topological insulator Bi1.5Sb0.5Te1.7Se1.3

Abstract

We report semiconductor to metal-like crossover in the temperature dependence of resistivity (ρ) due to the switching of charge transport from bulk to surface channel in three-dimensional topological insulator Bi1.5Sb0.5Te1.7Se1.3. Unlike earlier studies, a much sharper drop in ρ(T) is observed below the crossover temperature due to the dominant surface conduction. Remarkably, the resistivity of the conducting surface channel follows a rarely observable T 2 dependence at low temperature, as predicted theoretically for a two-dimensional Fermi liquid system. The field dependence of magnetization shows a cusp-like paramagnetic peak in the susceptibility (χ) at zero field over the diamagnetic background. The peak is found to be robust against temperature and χ decays linearly with the field from its zero-field value. This unique behavior of the χ is associated with the spin-momentum locked topological surface state in Bi1.5Sb0.5Te1.7Se1.3. The reconstruction of the surface state with time is clearly reflected through the reduction of the peak height with the age of the sample.

Magnetotransport properties and evidence of a topological insulating state in LaSbTe

“…. Similar field dependence of magnetic susceptibility has been reported for several topological insulators such as Bi 2 Se 3 , Bi 2 Te 3 , Sb 2 Te 3 , Bi 1.5 Sb 0.5 Te 1.7 Se 1.3[59][60][61] and narrow gap topological semimetals ZrTe 5 and LaBi[62,63], both with spin helical Dirac cone surface states.…”

In situ compensation method for high-precision and high-sensitivity integral magnetometry

“…In situ compensation method for ... 2 topological matter [27,28]. Despite this broad range of subjects, the investigated materials share one crucial common aspect: the objects of interest come on bulky substrates, or at least have to be fixed to a kind of rigid carrier, permitting mounting them onto adequate sample holders suitable for withstanding measurement cycles in wide ranges of temperature T and magnetic field H. However, the most popular multipurpose commercial SQUID magnetometers are not object-or element-selective probes, so the sought signal is very often (deeply) buried in the magnetic response of the ("nonmagnetic") carrier.…”

“…It has become routinely performed on a wide range of different types of samples such as ultrathin films [1,2,3,4,5,6], nanoparticles [7,8,9,10,11], nanowires [12,13], nanocomposites [14], quantum dots [15], graphene [16,17], dilute magnetic [18,19,20,21,22], and ferromagnetic semiconductor epilayers [23,24]. It currently enters the realms of organic spintronics [25], biology [26], and arXiv:1809.02346v3 [cond-mat.mtrl-sci] 5 Jul 2019 topological matter [27,28]. Despite this broad range of subjects, the investigated materials share one crucial common aspect: the objects of interest come on bulky substrates, or at least have to be fixed to a kind of rigid carrier, permitting mounting them onto adequate sample holders suitable for withstanding measurement cycles in wide ranges of temperature T and magnetic field H. However, the most popular multipurpose commercial SQUID magnetometers are not object-or element-selective probes, so the sought signal is very often (deeply) buried in the magnetic response of the ("nonmagnetic") carrier.…”

The temperature-independent paramagnetism susceptibility peak at zero magnetic fields in the non-topological WSe2 single crystal

“…A paramagnetic susceptibility peak at zero magnetic fields is reported in various kinds of topological materials. [1][2][3][4][5][6] It is speculated to originate from the spin texture at the Dirac point of the topological surface state. 7,8 The free alignment carrier spin is polarized under external magnetic fields and leads to the paramagnetic susceptibility peak.…”

“…However, none of these works support that the Fermi level is higher than the Dirac point in their systems. [1][2][3][4][5][6] Without this evidence, the mechanism of the paramagnetic susceptibility peak is questionable. Furthermore, a recent report shows a paramagnetic susceptibility peak at zero magnetic fields in a Bi 0.3 Sb 1.7 Te 3 topological insulator in which the Fermi level is below the Dirac point.…”