Search for enhanced magnetism at the interface between Bi${}_2$Se${}_3$ and EuSe

Abstract

Enhanced magnetism has recently been reported for the topological-insulator/ferromagnet interface Bi${}_2$Se${}_3$/EuS with Curie temperatures claimed to be raised above room temperature from the bulk EuS value of 16 K. Here we investigate the analogous interface Bi${}_2$Se${}_3$/EuSe. EuSe is a low-temperature layered ferrimagnet that is particularly sensitive to external perturbations. We find that superconducting quantum interference device (SQUID) magnetometry of Bi${}_2$Se${}_3$/EuSe heterostructures reveals precisely the magnetic phase diagram known from EuSe, including the ferrimagnetic phase below 5 K, without any apparent changes from the bulk behavior. Choosing a temperature of 10 K to search for magnetic enhancement, we determine an upper limit for a possible magnetic coercive field of 3 mT. Using interface sensitive x-ray absorption spectroscopy we verify the magnetic divalent configuration of the Eu at the interface without contamination by Eu3+, and by x-ray magnetic circular dichroism (XMCD) we confirm at the interface the magnetic hysteresis obtained by SQUID. XMCD data obtained at 10 K in a magnetic field of 6 T indicate a magnetic spin moment of mz,spin = 7 $\mu$B/Eu${}^{2+}$, in good agreement with the SQUID data and the expected theoretical moment of Eu2+. Subsequent XMCD measurements in zero field show, however, that sizable remanent magnetization is absent at the interface for temperatures down to about 10 K.

arXiv comment11 figures, 35 references

References in corpus (11)

• Topological Insulators
• Spin Transfer Torque Generated by the Topological Insulator Bi_2Se_3
• Magnetic impurities on the surface of a topological insulator
• Large magnetic gap at the Dirac point in a Mn-induced Bi${}_2$Te${}_3$ heterostructure
• Electric-field control of spin-orbit torque in a magnetically doped topological insulator
• Impurity-induced states on the surface of 3D topological insulators
• Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi${}_{1-x}$Mn${}_x{)}_2$Se${}_3$
• Surface magnetic ordering in topological insulators with bulk magnetic dopants
• Exchange interactions in europium monochalcogenide magnetic semiconductors and their dependence on hydrostatic strain
• Interface induced states at the boundary between a 3D topological insulator Bi${}_2$Se${}_3$ and a ferromagnetic insulator EuS
• Absence of magnetic-proximity effect at the interface of Bi${}_2$Se${}_3$ and (Bi,Sb)${}_2$Te${}_3$ with EuS

Cited by in corpus (3)

• Observation of nonlinear planar Hall effect in magnetic insulator/topological insulator heterostructures
• Epitaxial growth and magnetic characterization of EuSe thin films with various crystalline orientations
• Discovery of a high-temperature antiferromagnetic state and transport signatures of exchange interactions in a Bi2Se3/EuSe heterostructure