Fabrication and characterization of the gapless half-Heusler YPtSb thin films

Abstract

Half-Heusler YPtSb thin films were fabricated by magnetron co-sputtering method on MgO-buffered SiO 2 /Si(001) substrates. X-ray diffraction pattern and Energy dispersive X-ray spectroscopy confirmed the high-quality growth and stoichiometry.The temperature dependence of the resistivity shows a semiconducting-type behavior down to low temperature. The Hall mobility was determined to be 450 cm 2 /Vs at 300K, which is much higher than the bulk value (∼300 cm 2 /Vs). In-plane magnetoresistance (MR) measurements with fields applied along and perpendicular to the current direction show opposite MR signs, which suggests the possible existence of the topological surface states.PACS numbers: 71.20.Gj; 73.20 .At ---------------------------------------------------------------a) Electronic mail: wenhong.wang@iphy.ac.cn 2 Topological insulators (TIs) are of a new class of materials, which has a bulk band gap generated by strong spin-orbit coupling but contains gapless surface states. [1][2][3] Uniquely these states are robust with respect to disorder and exhibit high mobility due to the suppression of carrier backscattering. In addition, theses sates are spin-momentum locked, making TIs attractive for future spintronic devices and quantum computing applications as well. 4,5 Since the first theoretical prediction of a two-dimensional TI in an HgTe based quantum well, 6,7 several other families of materials for three-dimensional (3D) TIs have been proposed theoretically and well-studied experimentally. [8][9][10][11][12][13][14][15][16] For example, tetradymite semiconcuctors, such as Bi 2 Te 3 , Bi 2 Se 3 , and Sb 2 Te 3 are confirmed to be 3D TI with a single Dirac-cone on the surface, where the bulk band gap is as large as 0.3 eV, making the room temperature application possible. [8][9][10][11][12] However, a clear shortcoming of Bi 2 Te 3 family is that these materials cannot be made with coexisting magnetism, a much desired property for spintronic applications. Although doping can be used to achieve the magnetically ordered behavior, 17 this creates extra complexity in material growth and could introduce detrimental effects upon doping.Recently, half-Heusler ternary compounds with 18 valence electrons has been predicted to be 3D TI by alloying or proper stain engineering. [18][19][20][21] Most importantly, it was proposed that in the half-Heusler family the topological insulator allows the incorporation of superconductivity and/or magnetism. Among the experimentally studied TI candidates of half-Heusler materials, the gapless YPtSb is found to exhibit very good thermoelectric properties with a high figure of merit ZT of 0.2 and the high 3 Hall mobility, and thus has become the potential material of choice for both experimental and theoretical studies. 22,23 Development of devices utilizing TIs will require accurate characterization of the electronic transport. However, no transport investigation on the half-Heusler YPtSb thin films was carried out so far. The aim of this work is to try the way to obtain high quality YPtS...

Large Linear Magnetoresistance and Shubnikov-de Hass Oscillations in Single Crystals of YPdBi Heusler Topological Insulators

“…The recent discoveries of giant linear MR in Bi 2 Se 3 1011 and Bi 2 Te 3 1213 topological insulators (TIs) has brought renewed interest to linear MR. Because of their unusual surface states that are naturally zero bandgap with linear dispersion, TIs provide a perfect platform on which to study the origin of linear MR. Because some Heusler compounds have recently been predicted to be TIs141516, it is worth investigating whether large linear MR can also be observed in Heusler alloys. Considerable efforts have been devoted to the study of the electric structures and transport properties of a number of Heusler-based TIs171819202122232425. X-ray photoelectron spectroscopy results have shown that such Heusler-based materials as YPtSb, LaPtBi, LuPtSb and LuPdBi are gapless semiconductors with very high mobility212224 although large linear MR and desired Shubnikov-de Haas (SdH) quantum oscillations have not been observed experimentally in these materials.…”

“…Because of their unusual surface states that are naturally zero bandgap with linear dispersion, TIs provide a perfect platform on which to study the origin of linear MR. Because some Heusler compounds have recently been predicted to be TIs [14][15][16] , it is worth investigating whether large linear MR can also be observed in Heusler alloys. Considerable efforts have been devoted to the study of the electric structures and transport properties of a number of Heusler-based TIs [17][18][19][20][21][22][23][24][25] .…”

Robust tunability of magnetoresistance in half-HeuslerRPtBi(R=Gd, Dy, Tm, and Lu) compounds

“…In addition, the combination of strong spin-orbit coupling and non-centrosymmetric crystal structure (absence of an inversion center) makes Half-Heusler compounds a strong candidate for 3-dimensional topological materials [9][10][11]. Considerable efforts have been expended on experimental studies of the electronic structures and transport properties of Y-and Lu-based Half-Heusler materials [12][13][14][15]. In addition, the specific antiferromagnetic (AFM) ordering in GdPtBi may lead to an even more exotic state, proposed to be the AFM topological insulator [16,17].…”

Rare earth-based quaternary Heusler compoundsMCoVZ(M= Lu, Y;Z= Si, Ge) with tunable band characteristics for potential spintronic applications

“…In fact, we should point out that a large number of rare earth-containing ternary Heusler compounds based on the half-Heusler structure have already been prepared successfully (Hou, Wang, Xu, Zhang, Wei et al, 2015;Wang et al, 2012;Zhang et al, 2016;Mun et al, 2016). The rare earth-containing EQH compounds presented here have both novel electronic states and negative formation energies at the same time, and experimental realisation of them is feasible and imminent.…”