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The two‐dimensional (2D) materials InX (X = O, Se), experimentally available thus far, can become a ferromagnetic half metal under hole doping, though the charge neutral states of them are nonmagnetic semiconductors. Based on such an electronic characteristic, a theoretical model of magnetic tunnel junction (MTJ) is proposed composed only of one of the 2D InX. In doing so, the two semi‐infinite pieces of 2D InX in the half‐metallic state is assumed as the opposite electrodes which are separated by a strip of the same material but in its nonmagnetic state. Owing to the 2D nature of InX, the half metal electrodes of the InX device induced by hole doping can be achieved by using split gating technique. The numerical simulations identify a proper hole doping concentration, at which 100% tunneling magnetoresistance (TMR) ratios can be realized, accompanying an appreciable conductance of majority spin electron under parallel magnetization configuration. Under a finite bias voltage, the TMR ratio remains high. Therefore, the proposed device model is an ideal candidate for future spintronics applications. It enables electrical control of TMR and circumvents the detriment of hetero‐interface disorder inevitable in conventional MTJs. [ABSTRACT FROM AUTHOR]

The spin-exchange relaxation of electron spins directly affects the sensitivity of the atomic magnetometers. Rapid determination of the spin-exchange relaxation is essential. In this work, we propose a novel method for measuring the spin-exchange relaxation that allows being operated in the range of zero to earth-scale magnetic field. The longitudinal and transverse relaxation are synchronously extracted from the magnetic resonance linewidth and radio-frequency field amplitude corresponding to the maximum slope of the dispersive resonance curve. The spin-exchange relaxation is further obtained from the difference. The experimental results are consistent with the conventional linewidth fitting method in near-zero magnetic field and with the theoretical expectation in earth-scale magnetic field. This method not only improves authenticity compared to the conventional linewidth fitting method by considering the effect of rf field on relaxation, but also provides a fast and reliable measurement of the spin-exchange relaxation in earth-scale field. • A novel measurement of spin-exchange relaxation applicable in earth-scale field. • The transverse and longitudinal relaxation can be synchronously extracted. • Provide a way to evaluate the effect of spin-exchange relaxation suppression method. [ABSTRACT FROM AUTHOR]

We propose a novel method for measuring relaxation rates and Fermi-contact fields of the electron and nuclear spin ensembles rapidly and synchronously in spin-exchange relaxation-free (SERF) atomic comagnetometers based on the transient response. The transient response model of the comagnetometer is established by solving a set of Bloch equations. The decay rates and oscillation frequencies of the transient response as functions of the longitudinal magnetic field are investigated theoretically and experimentally. The total relaxation rate of the nuclear spin ensemble is obtained from its decay rate. A linear model is presented with a detailed mathematical derivation based on the decay rates and oscillation frequencies of the spin ensembles. The Fermi-contact fields of the spin ensembles and the slowing-down factor are extracted from the slope and intercept of the linear model. The total relaxation rate of the electron spins is obtained from the decay rates of the spin ensembles and the measured slowing-down factor. The validity of this method is further checked by the magnetic resonance (MR) method from a perspective of the electron resonance linewidth. Identification of these systematic parameters paves the way for operating the comagnetometers efficiently as well as the practical applications of the comagnetometers. [ABSTRACT FROM AUTHOR]