Yangsong Chen | Searcharxiv

arXiv2026

Switchable Magnetoelectric Transport in Graphene via a Van der Waals Multiferroic

Electric and magnetic control of transport properties at atomic interfaces is central to the development of next generation electronics and spintronics. Van der Waals multiferroics materials that simultaneously host dielectric and magnetic orders down to the monolayer limit offer a promising platform for such interfacial control, yet the realization of electronic functionalities that exploit the unique attributes of van der Waals multiferroics has largely remained elusive. Here, we realize a van der Waals heterostructure comprising graphene and the multiferroic CuCrP2S6, enabling gate-switchable magnetoelectric transport in graphene, mediated by the multiferroic layer. The charge-neutrality resistance peak of graphene exhibits pronounced hysteresis arising from polarization flip in the multiferroic state. Application of an in-plane magnetic field shifts this peak in a polarization-dependent manner, revealing magnetic-field-induced polarization modulation a direct signature of the magnetoelectric effect. Furthermore, cooling the device under an applied electric field enables domain control of the multiferroic order, allowing reversible switching of the interfacial magnetoelectric transport. These results provide the first demonstration of interfacial magnetoelectric transport in a vdW heterostructure, and establish a pathway for engineering two-dimensional van der Waals interfaces for functional device applications.

cond-mat.mes-hall↗

arXiv2024

Evolution of Critical Current Density in CaKFe$_4$As$_4$ with La-doping

Single crystals of (Ca$_{1-x}$La$_x$)KFe$_4$As$_4$ (0 <= x <=0.16) have been grown by using the self-flux method, and the evolution of physical properties including the critical current density (Jc) with La-doping has been investigated. Tc decreases monotonically with increasing x, while Jc at the same temperature and magnetic field increases initially and reach its maximum at x = 0.082. The increase in Jc is more obvious at low temperatures and high fields. At T = 5 K and H = 40 kOe, Jc reaches 0.34 MA/cm$^2$, which is ~4 times larger than that for pure crystals. It is also found that anomalous temperature dependence of Jc in CaKFe$_4$As$_4$ is wiped away as the La content is increased. However, Jc shows non-monotonic field dependence (peak effect) at high fields in crystals with large x. In addition, we found that despite weak anisotropy of H$_{c2}$, there is extremely large anisotropy of Jc up to ~15, which is most likely caused by novel planar defects in the crystal, similar to CaKFe$_4$As$_4$. Jc characteristics in (Ca$_{1-x}$La$_x$)KFe$_4$As$_4$ with disorder outside FeAs planes is compared with that in CaK(Fe$_{1-x}$Co$_x$)$_4$As$_4$ with disorder within FeAs planes.

cond-mat.supr-con↗