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Antiferromagnetic VdW Phase at the Interface of Sputtered Topological Insulator/Ferromagnet Bi2Te3/Ni80Fe20 Heterostructures



Nirjhar Bhattacharjee, Krishnamurthy Mahalingam, Adrian Fedorko, Valeria Lauter, Matthew Matzelle, Bahadur Singh, Alexander Grutter, Alexandria Will-Cole, Michael Page, Michael McConney, Robert Markiewicz, Arun Bansil, Don Heiman, Nian Sun


Magnetic ordering in topological insulators (TI) is crucial for breaking time-reversal symmetry (TRS) and thereby opening a gap in the topological surface states (TSSs) [1-6], which is the key for realizing useful topological properties such as the quantum anomalous Hall (QAH) effect, axion insulator state and the topological magnetoelectric effect. Combining TIs with magnetic materials can be expected to yield interfaces [26-28] with unique topological and magnetic phases but such interfaces largely remain unexplored. Here, we report the discovery of a novel antiferromagnetic (AFM) Van der Waals (VdW) phase at the interface of a sputtered c-axis oriented TI/FM (Bi2Te3/Ni80Fe20) heterostructure due to the formation of a Ni-intercalated Bi2Te3 VdW interfacial layer. The TI/FM heterostructure is shown to possess a significant spontaneous exchange bias and the presence of an AFM order at the interface via measurements of the hysteresis loop as well as the observation of compensated magnetic moments at the interface using polarized neutron reflectometry (PNR). An in-depth analysis of the structural and chemical properties of the interfacial AFM phase was carried out using selected area electron diffraction (SAED), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS). These studies show evidence of solid-state reaction between the intercalated Ni atoms and Bi2Te3 layers and of 31 the formation of topologically nontrivial magnetic VdW compounds. The Néel temperature of the interfacial AFM phase is 63 K, which is higher than that of typical magnetic topological insulators [53]. Our study shows how industrial CMOS-process-compatible sputtered TI/FM heterostructures can provide a novel materials platform for exploring the emergence of interfacial topological magnetic phases and high-temperature topological magnetic states.
Nature Materials


Bhattacharjee, N. , Mahalingam, K. , Fedorko, A. , Lauter, V. , Matzelle, M. , Singh, B. , Grutter, A. , Will-Cole, A. , Page, M. , McConney, M. , Markiewicz, R. , Bansil, A. , Heiman, D. and Sun, N. (2022), Antiferromagnetic VdW Phase at the Interface of Sputtered Topological Insulator/Ferromagnet Bi<sub>2</sub>Te<sub>3</sub>/Ni<sub>80</sub>Fe<sub>2</sub>0 Heterostructures, Nature Materials (Accessed August 10, 2022)
Created April 13, 2022