Enhancing electric-field control of ferromagnetism through nanoscale engineering of high-Tc MnxGe1−x nanomesh

Abstract

Voltage control of magnetism in ferromagnetic semiconductor has emerged as an appealing solution to significantly reduce the power dissipation and variability beyond current CMOS technology. However, it has been proven to be very challenging to achieve a candidate with high Curie temperature (Tc), controllable ferromagnetism and easy integration with current Si technology. Here we report the effective electric-field control of both ferromagnetism and magnetoresistance in unique MnxGe1−x nanomeshes fabricated by nanosphere lithography, in which a Tc above 400 K is demonstrated as a result of size/quantum confinement. Furthermore, by adjusting Mn doping concentration, extremely giant magnetoresistance is realized from ∼8,000% at 30 K to 75% at 300 K at 4 T, which arises from a geometrically enhanced magnetoresistance effect of the unique mesh structure. Our results may provide a paradigm for fundamentally understanding the high Tc in ferromagnetic semiconductor nanostructure and realizing electric-field control of magnetoresistance for future spintronic applications.

Engineering Magnetoresistance in MnxGe1−x System for Magnetic Sensor Application

“…Geometric-enhanced MR is another specific case of the orbital MR associated with the material shape [24,28]. Knudsen cells.…”

“…Therefore, we pay our attention to the pattern-assistant growth of Mn x Ge 1−x nanostructures and disclose their MR property. In this section, Mn x Ge 1−x nanomesh is demonstrated, which could simultaneously provide the nanostructure benefit [55] and large-scale uniform fabrication [28]. The growth of Mn x Ge 1−x nanomesh is also proceeded in the MBE chamber.…”

“…As the demand for the sensors with higher integration density and lower manufacturing cost is continuously growing, it calls for not only innovative sensor configuration but also novel material candidate with much higher sensitivity to magnetic field, higher compatibility with CMOS technology, and lower power consumption. Mn x Ge 1−x [26] as the silicon-compatible material appears to be an appealing candidate for application in MR sensors through the combined use of GMR [27] and geometric-enhanced MR [28]. In light of that, we give a review xbased MR sensors may set a new stage for the next-generation sensors with improved sensitivity, higher scalability, and higher compatibility with current CMOS technology.…”

Spontaneous shape transition of MnxGe1−x islands to long nanowires

“…Also, the tunability of the spin degrees of freedom in semiconducting materials offers a great potential for future spintronic applications. However, to achieve a reliable injection and detection of spin-polarized electrons in spintronic devices, appropriate heterostructures between semiconductors and magnetic alloys [9,10] need to be formed. Hence, a tailored growth process that preserves the injection efficiency and high Curie temperature is necessary.…”

Atomic layer doping of Mn magnetic impurities from surface chains at a Ge/Si hetero-interface

“…Si and Ge, have great potential as dilute magnetic semiconductors (DMS) for spintronic applications with complementary metaloxide-semiconductor (CMOS) compatibility [1][2][3] . Structural engineering is being intensively explored as a method to enhance the Curie temperature (T c ) of group IV based DMSs 4,5 . However, compared to III-V and II-VI semiconductors, e.g.…”