Local moment formation and magnetic coupling of Mn guest atoms in Bi${}_2$Se${}_3$: a low-temperature ferromagnetic resonance study

Abstract

We compare the magnetic and electronic configuration of single Mn atoms in molecular beam epitaxy (MBE) grown Bi${}_2$Se${}_3$ thin films, focusing on electron paramagnetic (ferromagnetic) resonance (EPR and FMR, respectively) and superconducting quantum interference device (SQUID) techniques. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) reveal the expected increase of disorder with increasing concentration of magnetic guest atoms, however, Kikuchi patterns show that disorder consists majorly of mum-scale 60deg twin domains in the hexagonal Bi${}_2$Se${}_3$ structure, which are promoted by the presence of single unclustered Mn impurities. Ferromagnetism below T${}_C$ ~ (5.4 +/- 0.3) K can be well described by critical scaling laws M(T) ~ (1-T/T${}_C$)${}^{\beta }$ with a critical exponent $\beta$ = (0.34 +/- 0.2)), suggesting 3D Heisenberg class magnetism instead of e.g. 2D-type coupling between Mn-spins in van der Waals gap sites. From EPR hyperfine structure data we determine a Mn${}^{2+}$ (d${}^5$, S = 5/2) electronic configuration with a g-factor of 2.002 for -1/2 --> +1/2 transitions. In addition, from the strong dependence of the low temperature FMR fields and linewidth on the field strength and orientation with respect to the Bi${}_2$Se${}_3$ (0001) plane, we derive magnetic anisotropy energies of up to K1 = -3720 erg/cm3 in MBE-grown Mn-doped Bi${}_2$Se${}_3$, reflecting the first order magneto-crystalline anisotropy of an in-plane magnetic easy plane in a hexagonal (0001) crystal symmetry. Across the ferromagnetic-paramagnetic transition the FMR intensity is suppressed and resonance fields converge the paramagnetic limit of a Mn${}^{2+}$ (d${}^5$, S = 5/2).

References in corpus (15)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• The development of ferromagnetism in the doped topological insulator Bi2-xMnxTe3
• Bulk superconducting phase with a full energy gap in the doped topological insulator Cu_xBi_2Se_3
• Ordering of magnetic impurities and tunable electronic properties of topological insulators
• Tailoring Magnetic Doping in the Topological Insulator Bi2Se3
• Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator
• Signatures of Dirac fermion-mediated magnetic order
• Suppressing twin formation in Bi2Se3 thin films
• Self-consistent theory of ferromagnetism on the surface of a topological insulator
• Dependence of superconductivity in CuxBi2Se3 on quenching conditions
• Strong out-of-plane magnetic anisotropy of Fe adatoms on Bi${}_2$Te${}_3$
• Spin dynamics and magnetic interactions of Mn dopants in the topological insulator Bi${}_2$Te${}_3$
• Non-magnetic ground state of Ni adatoms on Te-terminated bismuth chalcogenide topological insulators
• Topological insulator homojunctions including magnetic layers: the example of n-p type ($n$-QLs Bi${}_2$Se${}_3$/Mn-Bi${}_2$Se${}_3$) heterostructures

Cited by in corpus (2)

• Electron Spin Resonance Spectroscopy on Magnetic Van der Waals Compounds
• Magnetic properties of Mn-doped Bi${}_2$Se${}_3$ topological insulators: ab initio calculations