Electrically switchable van der Waals magnon valves

Van der Waals magnets have emerged as a fertile ground for the exploration of highly tunable spin physics and spin-related technology. Two-dimensional (2D) magnons in van der Waals magnets are collective excitation of spins under strong confinement. Although considerable progress has been made in understanding 2D magnons, a crucial magnon device called the van der Waals magnon valve, in which the magnon signal can be completely and repeatedly turned on and off electrically, has yet to be realized. Here we demonstrate such magnon valves based on van der Waals antiferromagnetic insulator MnPS3. By applying DC electric current through the gate electrode, we show that the second harmonic thermal magnon (SHM) signal can be tuned from positive to negative. The guaranteed zero crossing during this tuning demonstrates a complete blocking of SHM transmission, arising from the nonlinear gate dependence of the non-equilibrium magnon density in the 2D spin channel. Using the switchable magnon valves we demonstrate a magnon-based inverter. These results illustrate the potential of van der Waals anti-ferromagnets for studying highly tunable spin-wave physics and for application in magnon-base circuitry in future information technology.

Effective modulation of spin accumulation using a ferromagnetic/nonmagnetic bilayer spin channel

A lateral spin valve consisting of highly spin-polarized CoFeAl electrodes with a CoFeAl/Cu bilayer spin channel has been developed. Despite a large spin absorption into the CoFeAl capping channel layer, an efficient spin injection and detection using the CoFeAl electrodes enable us to observe a clear spin valve signal. We demonstrate that the nonlocal spin accumulation signal is significantly modulated depending on the relative angle of the magnetizations between the spin injector and absorber. The observed modulation phenomena is explained by the longitudinal and transverse spin absorption effects into the CoFeAl channel layer with the spin resistance model.

Ductile and metallic nature of Co2VZ (Z= Pb, Si, Sn) Heusler compounds: A First Principles Study

Herein, optoelectronic, elastic and magnetic properties of L21 structured Co2VZ (Z= Pb, Si, Sn) full Heusler compounds have been investigated by two methods. One is full potential linearized augmented plane wave (FP-LAPW) method as implemented in WIEN2k and second is pseudo potential method as implemented in Atomistic Tool Kit-Virtual NanoLab (ATK-VNL). All these compounds shows zero band gap in majority spin channel in the both simulation codes and a finite band gap are 0.33 and 0.54 eV in Co2VZ (Z= Pb, Sn) alloys (semiconducting) respectively. Due to minority-spin channel near the Fermi level as implemented in WIEN2k code and showing 100% spin polarization except Co2VSi (metallic) with zero band gap. These compounds found to be perfectly half-metallic ferromagnetic (HMF). However, above mentioned compounds shows finite band gaps in ATK-VNL code. The calculated magnetic moment of these compounds Co2VZ (Z= Pb, Si, Sn) are 3.00 and 3.00, 3.02 and 2.96, 3.00 and 3.00µB in WIEN2k and ATK-VNL codes respectively. Thus we have observed that the calculated vales by these simulation codes and Slater-Pauling rule have nice tuning. Optical properties of these compounds like as reflectivity, refractive index, excitation coefficient, absorption coefficient, optical conductivity and electron energy loss have been analyzed. Absorption coefficient and electron energy - loss function values are increases as we increase the value of energy. The vales of Pugh’s ratio B/G is greater than 1.75 for all compounds and showing ductile nature with positive value of Cauchy pressure (CP = C12 – C44) and shows metallic behavior of Co2VZ (Z= Pb, Si, Sn) compounds.