Electron Spin resonance of Gd3+ in three dimensional topological insulator Bi2Se3

T M Garitezi,C Rettori,R R Urbano,Z Fisk,G G Lesseux,C B R Jesus,T Grant,P G Pagliuso

doi:10.1088/1742-6596/592/1/012125

Abstract

Bi2Se3 has been claimed to be a three dimensional topological insulator (TI) with topologically protected metallic surface states with exotic properties. We have performed electron spin resonance (ESR) measurements on Gd3+ doped (x ≈ 0.01) Bi2Se3 single crystal grown from stoichiometric melt. For the studied crystals, our preliminary results revealed a partly resolved Gd3+ fine structure spectrum with Dysonian (metallic character) lines. At room temperature, the central line has a g ≈ 1.98, a linewidth ΔH ≈ 95 G and the spectra have a overall splitting of roughly 1300 Oe. As the temperature is decreased, the Gd3+ ESR ΔH of the central line presents a very small Korringa-like behavior b = ΔH/ΔT ≈ 0.013 Oe/K and nearly T-independent g-value. However, for T ≲ 40 K, ΔH shows a stronger narrowing effect evolving to Korringa-like behavior (b ≈ 0.15 Oe/K) for T ≲ 30 K. Concomitantly with the change in ΔH behavior, the Gd3+ central line g value starts to decrease reaching a value of 1.976 at T = 4.2 K. The ESR results are discussed in terms of possible effects of protected topological surface states enlightened by complementary data from macroscopic measurements.

Highlights

The ternary stannides compounds R3M4Sn13 (R = rare-earth or alkaline-earth, M = transition metal) [1] have recently regained interest due to the possible interplay between superconductivity and the occurrence of a structural quantum critical point, as claimed in Ca3Ir4Sn13 (Tc ∼ 7 K) and in Sr3Ir4Sn13 (Tc ∼ 5 K) [2]
In the present work we have extended our early study on Eu3Ir4Sn13 to higher pressures (P < 26 kbar), and have investigated the effects of magnetic field on the electronic transport properties of the intermetallic Eu3Ir4Sn13
Bellow T ∗, a hump-like feature is discernible in the electrical resistivity at zero applied pressure

Summary

Introduction

Our previous pressure dependent resistivity measurements on a Eu3Ir4Sn13 single crystal up to 8 kbar have revealed that T ∗ is strongly pressure-dependent and decreases linearly with increasing pressure, while the magnetic ordering temperature TN is weakly affected in the pressure range investigated [5]. Temperature dependent DC electrical resistivity measurements were carried out in a Physical Properties Measurement System (PPMS), with applied magnetic fields up to H = 90 kOe and external pressure up to P = 26 kbar, by means of the conventional four-contact configuration.

Results

Conclusion