Half‐Valley Ohmic Contact: Contact‐Limited Valley‐Contrasting Current Injection

Abstract

The 2D ferrovalley semiconductor (FVSC) with spontaneous valley polarization offers an exciting material platform for probing Berry phase physics. How FVSC can be incorporated in valleytronic device applications, however, remain an open question. Here, the concept of metal/semiconductor (MS) contact into the realm of valleytronics is generalized. A half‐valley Ohmic contact is proposed based on FVSC/graphene heterostructure, where the two valleys of FVSC separately forms Ohmic and Schottky contacts with those of graphene, thus allowing current to be valley‐selectively injected through the ‘Ohmic’ valley while being blocked in the ‘Schottky’ valley. A theory of contact‐limited valley‐contrasting current injection is developed and such transport mechanism can produce gate‐tunable valley‐polarized injection current. Using RuCl2/graphene heterostructure as an example, a device concept of valleytronic barristor is illustrated, where high valley polarization efficiency and sizable current on/off ratio, can be achieved under experimentally feasible electrostatic gating conditions. These findings uncover contact‐limited valley‐contrasting current injection as an efficient mechanism for valley polarization manipulation, and reveals the potential of valleytronic MS contact as a functional building block of valleytronic device technology.

Tunable abundant valley Hall effect and chiral spin–valley locking in Janus monolayer VCGeN4

“…Besides this, the FV properties are widely applied in multiple functional nanodevices. Recently, Feng et al proposed a novel concept of contact-limited valley-contrasting current injection, 77 which can generate gate-tunable valley-polarized injection current. It provides a new idea for VP manipulation.…”

Electric-field-driven ferromagnetic response in Janus MnReX3 (X = Se, S) monolayer via asymmetric interface orbital hybridization

“…The electric field strength should be within the breakdown limit of the gate dielectric, because it is the more common and practical approach for majority of device applications. Based on previous report [32,33], the electric field strength from -2 V nm −1 to 2 V nm −1 is adopted to disclose their possible magnetic responses. Interestingly, the magnetic moment as a function of external electric field is calculated in figure S5 (supporting information), in which they are not sensitive to the external electric field.…”

Coexisting Ferroelectric, Ferromagnetic, and Ferrovalley Polarizations in Single Quintuple Layer ReAlGe2X6 (X = S, Se)

“…These studies have demonstrated novel material properties that can be harnessed for innovative device functionalities. Furthermore, several valleytronic devices have been proposed, such as valley-spin logic gates, reversible valleytronic logic, and half-valley Ohmic contact, , which highlights the potential application of valleytronic systems in next-generation electronic devices. In these materials, ferroic orders primarily arise from symmetry-breaking induced orbital order polarization, fostering a significant electric-valley coupling criterion for the advancement of sophisticated control unit devices. ,− However, intriguing electric-valley coupling is rarely observed in natural monolayer structures.…”