Nonsaturating large magnetoresistance in semimetals

Abstract

The rapidly expanding class of quantum materials known as topological semimetals (TSMs) displays unique transport properties, including a striking dependence of resistivity on applied magnetic field, that are of great interest for both scientific and technological reasons. So far, many possible sources of extraordinarily large nonsaturating magnetoresistance have been proposed. However, experimental signatures that can identify or discern the dominant mechanism and connect to available theories are scarce. Here we present the magnetic susceptibility (χ), the tangent of the Hall angle (tan θ H ), along with magnetoresistance in four different nonmagnetic semimetals with high mobilities, NbP, TaP, NbSb 2 , and TaSb 2 , all of which exhibit nonsaturating large magnetoresistance (MR). We find that the distinctly different temperature dependences, χ(T), and the values of tan θ H in phosphides and antimonates serve as empirical criteria to sort the MR from different origins: NbP and TaP are uncompensated semimetals with linear dispersion, in which the nonsaturating magnetoresistance arises due to guiding center motion, while NbSb 2 and TaSb 2 are compensated semimetals, with a magnetoresistance emerging from nearly perfect charge compensation of two quadratic bands. Our results illustrate how a combination of magnetotransport and susceptibility measurements may be used to categorize the increasingly ubiquitous nonsaturating large magnetoresistance in TSMs.nonsaturating magnetoresistance | magnetic susceptibility | Weyl semimetals | topological semimetals

Dynamical density and spin response of Fermi arcs and their consequences for Weyl semimetals

“…The Pauli spin susceptibility, defined as the static longitudinal spin susceptibility for q → 0, is found to vanish identically [62]. This can be attributed to the spinmomentum locking in the Weyl Hamiltonian near the nodes and has recently been observed in the candidate materials NbP and TaP [63]. The vanishing Pauli susceptibility holds true even beyond the linear-response regime [62].…”

Strong correlation between mobility and magnetoresistance in Weyl and Dirac semimetals

“…It is essential to examine the variability in MR with respect to the mobility in these compounds. We gathered these two quantities for various compounds at ∼2 K and 9 T from literature [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][39][40][41][42]. As MR varies with the field, it is more valid to consider the slope of the MR with the field than considering the value of MR in a fix field.…”

“…Depending on their degeneracy, topological semimetals are further distinguished and classified into Weyl semimetals (WSM) and Dirac semimetals. The discovery of Weyl fermions in transition metal monopnictides [1][2][3][4][5][6] has facilitated the discovery of additional Dirac and Weyl semimetals in the various families of compounds [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Thermoelectric transport coefficients of a Dirac electron gas in high magnetic fields

“…The result for the Seebeck (S xx ) and Nernst (S xy ) coefficients depends strongly on the Hall angle (tan ϑ H = σ xy /σ xx ), which is mainly determined by the ratio of charge carrier density and the impurity density. Based on experimental results for the Hall angle 27 we will assume σ xy > σ xx . This is in good agreement with the assumption that the impurity density is not too high.…”

“…20 and 21). Under an external magnetic field some of these are the chiral anomaly 22 and as a consequence negative magnetoresistance 23 and a non-saturating linear magnetoresistance 15,[24][25][26][27] . Furthermore, several thermoelectric experiments were carried out in an external magnetic field [28][29][30][31][32] .…”