title: Room-temperature electric-field controlled ferromagnetism in Mn0.05Ge0.95 quantum dots.
abstract: Room-temperature control of ferromagnetism by electric fields in magnetic semiconductors has been actively pursued as one of important approaches to realize practical spintronic and nonvolatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (T(c) > 300 K) and controllable ferromagnetism at room temperature has continued for nearly a decade. Recently, Mn(0.05)Ge(0.95) quantum dots (QDs) were demonstrated to have a T(c) above 300 K. However, the field control of ferromagnetism based on hole-mediated effect remained at low temperatures and thus prohibited spintronic devices operable at ambient environment. Here, we report a successful demonstration of electric-field control of ferromagnetism in the Mn(0.05)Ge(0.95) quantum dots up to 300 K. We show that, by using quantum structure, high-quality material can be obtained and effective hole mediation due to quantum confinement effect can be achieved. Upon the application of gate bias to a metal-oxide-semiconductor (MOS) capacitor, the ferromagnetism of the channel layer, that is, the Mn(0.05)Ge(0.95) quantum dots, was manipulated through the change of hole concentration. Our results are fundamentally and technologically important toward the realization of room-temperature spin field-effect transistors and nonvolatile spin logic devices.
authors.affiliation: Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA. xiu@ee.ucla.edu
authors.forename: Faxian
authors.initials: F
authors.lastname: Xiu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Kim
authors.forename: Pramey
authors.initials: P
authors.lastname: Upadhyaya
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Xufeng
authors.initials: X
authors.lastname: Kou
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.forename: R K
authors.initials: RK
authors.lastname: Kawakami
authors.forename: Jin
authors.initials: J
authors.lastname: Zou
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang