Magnetoelectric manipulation and enhanced operating temperature in antiferromagnetic Cr₂O₃ thin film

Abstract

Electrically controllable antiferromagnets will play a prominent role in the development of future spintronics. These materials offer a way to realize innovative low-energy-consumption, high-speed, highly integrated spintronic devices for storage, memory, and logic use. The magnetoelectric manipulation of antiferromagnetic spin in Cr2O3 is one of the most promising ways to achieve such devices. Crucial problems toward device applications are 1) the establishment of high-quality Cr2O3 thin-film fabrication techniques and the demonstration of the adaptability of such films for high-performance devices, and 2) the enhancement of the operating temperature in order to ensure sufficient stability for room-temperature operations. In this review, we summarize the recent progress made in Cr2O3 thin-film research, especially focusing on the magnetoelectric manipulation of antiferromagnetic spin and material development for achieving a higher operating temperature in Cr2O3 thin films.

Roadmap on Magnetoelectric Materials and Devices

“…This finding, which made it possible to electrically control the state of the antiferromagnetic domains-thus overcoming one of the previously mentioned hindranceswas subsequently demonstrated in Cr2O3 thin films [71], in which comfortably high TN values may also be possible according to recent studies. (B-doped Cr2O3 thin films with TN values up to ~400K have been reported [72] following a theoretical prediction [73]) Although several technical issues still need to be improved, such as the large manipulation energy of the exchange bias in thin films compared to bulk crystals [74], the scarcity of RT magnetoelectrics may grant Cr2O3 a role in the future development of spintronic and memory applications based on the magnetoelctric effect.…”

Manipulation of Antiferromagnetic Spin Using Tunable Parasitic Magnetization in Magnetoelectric Antiferromagnet

“…Cr 2 O 3 is one of few materials which can achieve 180° manipulation of antiferromagnetic spin in electrical mean. Thus far, electrical manipulation of antiferromagnetic spin in Cr 2 O 3 /FM exchange bias systems has been extensively investigated, for future storage/memory/logic applications . This research has developed detection techniques which access the 180° difference in the antiferromagnetic spin .…”

“…The electrical switching requires larger energy when it is against the exchange bias . Moreover, because the exchange bias is an interface phenomenon, the energy barrier due to the exchange bias increases with decreasing Cr 2 O 3 thickness, and switching the antiferromagnetic spin for both direction becomes increasingly difficult . However, the additional Zeeman energy of M Cr2O3 in doped Cr 2 O 3 can compensate and minimize the energy barrier, which results in a reduction in the switching electric field.…”

“…As estimated in ref. , the electric field required to overcome the exchange bias barrier for a 10‐nm Cr 2 O 3 system is ≈10 MV cm −1 when H fr ≈ 10 kOe is applied. This value is too large to be realistically applied, and electrical switching of the antiferromagnetic spin is impossible.…”

Perspective: voltage control of magnetization in multiferroic heterostructures

“…Note that the mechanism shown in Fig. 2c is also applicable to a ferromagnet/Cr 2 O 3 heterostructure (see a recent experiment with Cr 2 O 3 thin films in [ 8 ]). Such ferromagnet/Cr 2 O 3 heterostructure is, however, not multiferroic, because Cr 2 O 3 is magnetoelectric but not ferroelectric.…”