Zero-net-magnetization hybrid magnet

Zero-net-magnetization magnets possess ultradense and ultrafast application potential, benefiting from their intrinsic zero stray field and terahertz dynamics characteristics. Herein, we propose the concept of zero-net-magnetization hybrid magnet, in which magnetic atoms with opposite spin polarization are partially coupled via spatial inversion ($P$) symmetry, partially via rotation/mirror ($C/M$) symmetry or partially without any symmetry correlation. From a local perspective and neglecting the interactions between local regions, hybrid magnet can be regarded as being composed of $PT$-antiferromagnet (possessing the combined symmetry ($PT$) of $P$ and time-reversal ($T$)), altermagnet, or fully compensated ferrimagnet. To realize hybrid magnet, we propose that such system can be constructed by forming heterojunction with three types of zero-net-magnetization magnetic monolayers. We mainly investigate the heterojunction composed of two kinds of zero-net-magnetization magnets, among which one type corresponds to fully compensated ferrimagnet. When heterojunction hybrid magnet exhibits a type-II band alignment, only one of electron doping and hole doping can induce a net magnetic moment, while the other hardly generates any net magnetization. Taking the heterojunction constructed by $PT$-antiferromagnet and fully compensated ferrimagnet as an example, we verify our proposal by means of the tight-binding (TB) model. Finally, taking the $\mathrm{Cr_2C_2S_6}$/$\mathrm{CrMoC_2S_6}$ heterojunction as an example, we perform first-principles calculations combined with electric field modulation to validate our TB model and theoretical proposal.