Study of proximity-coupled magnetic anisotropy in V-doped SnTe using spin resonance and magnetic measurements

SnTe is a topological crystalline insulator with topological surface states (TSSs) protected by crystal symmetries. This, along with an associated Berry-phase π, results in a positive quantum correction in electrical conductivity, known as weak antilocalization (WAL). The applied magnetic field breaks down the TSS protection, resulting in a cusp-like negative magnetoconductance (MC). SnTe has a large amount (10²¹ cm^-3) of Sn vacancies, leading to considerable bulk conductivity with a parabolic background over the WAL MC. In this work, we observe an enhancement of the WAL signal in V-doped SnTe using electron spin resonance (ESR) measurements by substituting Sn vacancies with V atoms and charge-transfer-induced and temperature-dependent localization of itinerant carriers, called bound magnetic polarons (BMPs), which increases the effective mass of both electrons and holes and reduces bulk conductivity, as a consequence of magnetic anisotropy. Additionally, spin-orbit-coupling (SOC) induced spin canting, BMPs, interstitial, and substitutional occupation of V-impurities lead to competing ferromagnetic and antiferromagnetic proximity-coupled itinerant carrier-mediated Ruderman-Kittel-Kasuya-Yosida interaction in bare and V-doped SnTe, as evidenced by normal and parallel components of internal magnetic fields, observed in low-temperature ESR absorption spectral and temperature-dependent DC magnetization measurements. This proximity-coupled magnetic anisotropy makes V-doped SnTe a potential candidate for catalysis, thermoelectric, and spintronic applications. Density functional theory computations support SOC-induced spin canting, proximity-coupled magnetic order, and the charge transfer between V, Sn, and Sn vacancies.