Kavli Affiliate: Gang Su
| First 5 Authors: Jia-Wen Li, Gang Su, Bo Gu, ,
| Summary:
The development of room-temperature tunable magnetic semiconductors is
crucial for the advancement of low-power, high-performance information
technologies. Using density functional theory calculations, we propose a series
of two-dimensional magnetic semiconductors with critical temperature above room
temperature, including three ferromagnetic and two antiferromagnetic
semiconductors.Their stability is confirmed through phonon spectra, molecular
dynamics simulations, and formation energy calculations. In particular, we
demonstrate a ferromagnetic bipolar magnetic semiconductor (BMS), Cr2NiSe4,
formed via Ni intercalation into bilayer CrSe2, which exhibits a 0.40 eV band
gap and a Curie temperature of 352 K. Nonvolatile carrier spin polarization
control in Cr2NiSe4 is achieved by switching the ferroelectric polarization of
an Al2Se3 substrate. Switching the ferroelectric state of monolayer Al2Se3
induces a BMS-to-half-metal transition. Reversing the polarization of bilayer
Al2Se3 yields a half-metallic Cr2NiSe4 with fully opposite carrier spin
polarization. Furthermore, we propose a multiferroic nonvolatile memory design:
write operations are controlled by the ferroelectric polarization state of
bilayer Al2Se3, while read operations rely on detecting the distinct carrier
spin polarizations of Cr2NiSe4. Our work reports a two dimensional BMS with
Curie temperature above room temperature and presents a feasible strategy for
its nonvolatile electrical control.
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