Synthesis and thermoelectric properties of Rashba semiconductor BiTeBr with intensive texture

Abstract

Bismuth tellurohalides with Rashba-type spin splitting exhibit unique Fermi surface topology and are developed as promising thermoelectric materials. However, BiTeBr, which belongs to this class of materials, is rarely investigated in terms of the thermoelectric transport properties. In the study, polycrystalline bulk BiTeBr with intensive texture was synthesized via spark plasma sintering (SPS). Additionally, its thermoelectric properties above room temperature were investigated along both the in-plane and out-plane directions, and they exhibit strong anisotropy. Low sound velocity along two directions is found and contributes to its low lattice thermal conductivity. Polycrystalline BiTeBr exhibits relatively good thermoelectric performance along the in-plane direction, with a maximum dimensionless figure of merit (ZT) of 0.35 at 560 K. Further enhancements of ZT are expected by utilizing systematic optimization strategies.

Defect Compensation Weakening Induced Mobility Enhancement in Thermoelectric BiTeI by Iodine Deficiency

“…After introducing I deficiency, the concentration of intrinsic and antisite defects reduces and suppresses the defects‐induced carrier scattering to enhance the carrier mobility. Besides Cu intercalation and I deficiency, replacing I with smaller isoelectronic Br ion might also be a feasible way to improve the carrier mobility via the suppression of antisite defect, which has confirmed by previous work, [34] and large carrier mobility than 200 cm 2 V −1 s −1 is also reported for pristine BiTeBr at 300 K [47] …”

“…I antisite defects reduces and suppresses the defects-induced carrier scattering to enhance the carrier mobility. Besides Cu intercalation and I deficiency, replacing I with smaller isoelectronic Br ion might also be a feasible way to improve the carrier mobility via the suppression of antisite defect, which has confirmed by previous work, [34] and large carrier mobility than 200 cm 2 V À 1 s À 1 is also reported for pristine BiTeBr at 300 K. [47] The Seebeck coefficient and calculated powder factor (PF = PF = σS 2 ) are displayed in Figure 5. All Seebeck coefficients (Figure 5a and 5b) show negative values in the measured temperature range, which is consistent with the negative Hall coefficient and indicates n-type electrical conduction.…”

Transport properties of topologically non-trivial bismuth tellurobromides BinTeBr

“…10 The S values for the three Bi 2 TeBr specimens are significantly larger than that reported for Bi 2 TeI, with S max being twice as high for Bi 2 TeBr than that for Bi 2 TeI. 15 In contrast to the bismuth-poor materials, 36 Fig. 2(b) indicates positive S values for Bi 2 TeBr and Bi 3 TeBr.…”

Electrically Controlled Spin Injection from Giant Rashba Spin–Orbit Conductor BiTeBr

“…The recently discovered class of semiconductor materials, bismuth tellurohalides (BiTeX, where X is a halo-gen element) feature a giant Rashba spin splitting of the bulk bands [25][26][27] as experimentally verified by spin-and angle-resolved photoemission spectroscopy [28][29][30][31][32][33]. This unique spin texture makes them highly desirable for various spintronic applications.…”

“…The recently discovered class of semiconductor materials, bismuth tellurohalides (BiTeX, where X is a halogen element) feature a giant Rashba spin splitting of the bulk bands − as experimentally verified by spin- and angle-resolved photoemission spectroscopy. − This unique spin texture makes them highly desirable for various spintronic applications. Further interesting properties of these highly polar semiconductor materials include the bulk rectification effects, pressure-induced topological phase, − superconductivity, , and out-of-plane spin textures caused by coupling to orbital degree of freedom …”