Coherent Hopping Transport and Giant Negative Magnetoresistance in Epitaxial CsSnBr₃

Abstract

High-quality single-crystal inorganic halide perovskites have begun to attract interest for future quantum devices applications. In this work, we focus on the quantum transport properties of single-crystal epitaxial halide perovskites and present low-temperature quantum magnetotransport measurements on thin film devices of single-crystal cesium tin bromide (CsSnBr3) at low temperature. We demonstrate that the system exhibits two-dimensional (2D) Mott variable range hopping (VRH) transport with a giant negative magnetoresistance. This large negative magnetoresistance can be described by the Nguyen-Spivak-Shkovskii (NSS) model which describes the quantum interference of different directed hopping paths of charge carriers. Based on this model, we extract the temperature-dependent hopping length of charge carriers in epitaxial CsSnBr3, estimate their localization length, and find a lower bound for their phase coherence length of ~ 100 nm at low temperatures. These new observations add to a growing body of experimental evidence that demonstrate that epitaxial halide perovskites are emerging as a new material class for the study of lowdimensional quantum coherent transport phenomena.

Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr3 Perovskite

“…If the ordering remains that observed for bulk samples, one expects the spontaneous polarization and Rashba coefficients to be enhanced. Tantalizingly, others have grown CsSnBr 3 under several percent compressive strain, − suggesting similar magnitudes of tensile strain may be possible.…”

“…While NQR indicated a second-order transition at ∼85 K to a phase with at least seven distinct Br sites, no further details about the structure, symmetry, or properties of this phase were reported . Tantalizingly, this compound exhibits the narrowest band gap of (single) perovskite group 14 bromides (an important predictor of Rashba effect strength), and its inorganic composition has allowed for the growth of epitaxial thin films. − …”

Localization effect in single crystal of RuAs2

“…The longitudinal voltage V xx was detected with the nanovoltmeter. Using the x-ray Laue photograph, the sample was cut precisely along the crystallographic axes with typical dimensions of 2.9×0.641×0.152 mm 3 , where the longest dimension was along the [110] axis.…”

“…The phase shift caused by the magnetic field will suppress the interference and lead to negative magnetoresistance (NMR). [2,3] Weak antilocalization (WAL), an effect opposite to the weak localization (WL), appears as the positive magnetoresistance (MR) with a sharp cusp in low fields. [4,5] WAL is always expected in systems with strong spin-orbit scattering or coupling, in which the strong spin-orbit interaction will lower the probability of backscattering.…”

“…The conductive process is known as variable range hopping (VRH), where the electrons can tunnel between localized states with the assistance of phonons. [2,3] Transition-metal dipnictides XPn 2 (X = transition metal; Pn = P, As, Sb, Bi) are a large family of materials with rich physical properties. In these materials, NbAs 2 /TaAs 2 are weak topological insulators with extremely large MR, and will evolve into Weyl semimetals under magnetic field.…”