[23p-B201-1~12] 10.4 Spintronics in semiconductor, topological material, superconductor, and multiferroics

△ [23p-B201-4] Giant voltage-controllable magnetoresistance switching in Ge short-channel devices with epitaxial ultra-thin Fe electrodes

〇Shun Tsuruoka¹, Yuriko Tadano¹, Ahn Le Duc¹, Masaaki Tanaka^1,2, Shinobu Ohya^1,2 (1.The Univ. Tokyo, 2.The Univ. Tokyo CSRN)

Keywords:spintronics, spin-valve, germanium

Tunneling anisotropic magnetoresistance (TAMR) is an interfacial effect between a ferromagnet and a non-magnetic material where the tunneling resistance depends on the orientation of the magnetization. Since TAMR originates from spin-orbit coupling (SOC), large TAMR is observed in materials with strong SOC such as GaMnAs, while observing large TAMR in weak SOC materials has been difficult. In this study, we fabricated and characterized a Ge-based all-epitaxial single-crystalline lateral device with a short channel. We have grown Fe/ MgO/ Ge:B/ Ge on a Ge (001) substrate using molecular-beam-epitaxy (MBE), and then we reduced the Fe layer to less than 1 nm by Ar milling to induce a perpendicular magnetic anisotropy component. We have fabricated a short-channel device with a channel length of a few tens of nm by electron beam lithography and Ar milling. In the perpendicular magnetic-field dependence of the source-drain resistance at 3 K, we observed switching between the high-resistance state and the low-resistance state at a threshold field, and it increases with the increasing voltage. The magnetoresistance (MR) ratio increases with the increasing voltage, and when it is 9 V, the MR ratio reaches over 10000%. These results suggest that the magnetoresistance switching reflects the modulation of the magnetization direction induced both by electric and magnetic fields.