Observation of open-orbit Fermi surface topology in the extremely large magnetoresistance semimetalMoAs2

Abstract

While recent advances in band theory and sample growth have expanded the series of extremely large magnetoresistance (XMR) semimetals in transition metal dipnictides T mPn 2 (T m = Ta, Nb; Pn = P, As, Sb), the experimental study on their electronic structure and the origin of XMR is still absent. Here, using angle-resolved photoemission spectroscopy combined with first-principles calculations and magnetotransport measurements, we performed a comprehensive investigation on MoAs 2 , which is isostructural to the T mPn 2 family and also exhibits quadratic XMR. We resolve a clear band structure well agreeing with the predictions. Intriguingly, the unambiguously observed Fermi surfaces (FSs) The emergence of novel states in condensed matter is not only classified by the typical spontaneous symmetry breaking, but also by their topology, i.e., the topologically protected quantum states [1][2][3]. The discovery of such symmetry protected states of matter in two-dimensional (2D) [4-6] and three-dimensional (3D) topological insulators [7], node-line semimetals [8,9], topological crystalline insulators [10,11], and Dirac and Weyl semimetals [12][13][14][15][16][17], has attracted tremendous interests in condensed matter physics and material science. The magnetotransport behavior of these states is often unusual, such as linear transverse magnetoresistance (MR) and negative longitudinal MR in Dirac and Weyl semimetals [18][19][20][21][22][23][24], and more generally, extremely large transverse MR (XMR) in nonmagnetic semimetals [25][26][27][28][29][30].Recently, the discovery of XMR in a class of transition metal dipnictides T mPn 2 (T m = Ta, Nb; Pn = P, As, Sb) [31][32][33][34][35][36] has sparked immense interests for understanding the underlying mechanism of quadratic XMR and exploring novel quantum states arising from nontrivial topology. Another two series of semimetals possessing quadratic XMR behavior and rich topological characteristics are the ZrSiS family [37][38][39] and LnX (Ln = La, Y, Nd, or Ce; X = Sb/Bi) series [40][41][42][43][44][45][46], whose electronic structures have been considerably studied both in theory and experiment [47][48][49][50][51][52][53]. While the band structures of the T mPn 2 series have been theoretically characterized in several work [32][33][34]54], experimental observations have not yet been reported. It is widely believed that the large positive MR in semimetals is intimately related to their underlying electronic structures. Therefore, a systematic and unambiguous experimental study on the electronic structure of the T mPn 2 family is urgently demanded. Eventually, we suggest the open-orbit Fermi surface (FS) topology as another candidate mechanism to explain the XMR, in addition to the earlier proposed origins like nontrivial band topology [40], forbidden backscattering at zero field [55], and electron-hole compensation [56].In this Letter, we employ systematic angle-resolved photoemission spectroscopy (ARPES), first-principles calculations, and magnetotransport measurements o...

Extremely large magnetoresistance from electron-hole compensation in the nodal loop semimetal ZrP$_2$

“…70-230 meV below the Fermi level. Additionally, open-orbit Fermi surface topology as in MoAs 2 [3,49] can be ruled out as the origin. A similar situation was found for the type-II Weyl semimetal WP 2 for which the XMR was attributed to e-h compensation despite the existence of Weyl nodes [43].…”

“…Topological semimetals have attracted considerable scientific interest owing to their unique electronic structure and unconventional transport properties, such as extremely large magnetoresistance (XMR) [1][2][3][4][5][6] and planar Hall effect [7,8], as well as their deep connection with the high-energy particle physics [9]. These unusual properties not only pave the way for future electronic and spintronic devices, but also provide a test-bed for our current models of transport theories [10].…”

“…In early transition metal dipnictides (TMDPs), nontrivial topology is often accompanied by unsaturated XMR [1,3,[28][29][30][31]. Elements highlighted in Fig.…”

Extremely large magnetoresistance and compensated Fermi surfaces in the antiferromagnetic semimetal YbAs

“…An extremely large magnetoresistance (XMR) reaching values up to ∼ 10 4 -10 6 % has been observed in some semimetals in moderately high magnetic fields [1][2][3][4][5][6]. This effect has mainly been attributed to electron-hole carrier compensation [1,[7][8][9] or the presence of topologically non-trivial surface states [2][3][4].…”

First-principles study of electronic structure and Fermi surface in semimetallic YAs

“…YSb is a typical example of monopnictides exhibiting nonsaturating large magnetoresistance MR ∼ 10 5 % in a field of 9 T at low temperatures [19]. MR varies with B quadratically in weak fields and almost linearly in strong fields, in a manner observed in many semimetallic materials, such as (Nb,Ta)As, (Nb,Mo,Ta)As 2 , (Pd,Pt)Sn 4 or WTe 2 [8,9,10,12,11,13,14,15].…”