Search

Sr2FeMoO6-δ (SFMO) double perovskite is a promising candidate for room-temperature spintronic applications, since it possesses a half-metallic character (with theoretically 100% spin polarization), a high Curie temperature of about 415 K and a low-field magnetoresistance (LFMR). The magnetic, resistive and catalytic properties of the double perovskite SFMO are excellent for spintronic (non-volatile memory), sensing, fuel cell and microwave absorber applications. However, due to different synthesis conditions of ceramics and thin films, different mechanisms of electrical conductivity and magnetoresistance prevail. In this work, we consider the occurrence of a weak localization effect in SFMO commonly obtained in disordered metallic or semiconducting systems at very low temperatures due to quantum interference of backscattered electrons. We calculate the quantum corrections to conductivity and the contribution of electron scattering to the resistivity of SFMO. We attribute the temperature dependence of SFMO ceramic resistivity in the absence of a magnetic field to the fluctuation-induced tunneling model. We also attribute the decreasing resistivity in the temperature range from 409 K to 590 K to adiabatic small polaron hopping and not to localization effects. Neither fluctuation-induced tunneling nor adiabatic small polaron hopping favors quantum interference. Additionally, we demonstrate that the resistivity upturn behavior of SFMO cannot be explained by weak localization. Here, the fitted model parameters have no physically meaningful values, i.e., the fitted weak localization coefficient (B′) was three orders of magnitude lower than the theoretical coefficient, while the fitted exponent (n) of the electron–electron interaction term (CnTn) could not be assigned to a specific electron-scattering mechanism. Consequently, to the best of our knowledge, there is still no convincing evidence for the presence of weak localization in SFMO. [ABSTRACT FROM AUTHOR]

Antiphase boundaries (APB) in strontium ferromolybdate induce antiferromagnetically coupled spins of the Fe ions at the boundary affecting both the magnetic properties and the electron transport across the boundary. Herein, first, 3D presentation of the APB in strontium ferromolybdate is presented. For the first time, the weighted antiferromagnetic (AF) modulus, the bulk ferrimagnetic exchange stiffness constant, and the AF exchange stiffness constant across the APB of strontium ferromolybdate are estimated. This is done by analyzing carefully selected experimental data of the magnetoresistance (MR). The boundary width and boundary energy are calculated by means of Kittel's theory of the structure of ferromagnetic domains in films and small particles. The evaluation of these parameters deepens the understanding of MR in strontium ferromolybdate ceramic and thin‐film samples possessing a high density of APBs. [ABSTRACT FROM AUTHOR]

Antiphase boundaries (APB) in strontium ferromolybdate induce antiferromagnetically coupled spins of the Fe ions at the boundary affecting both the magnetic properties and the electron transport across the boundary. Herein, first, 3D presentation of the APB in strontium ferromolybdate is presented. For the first time, the weighted antiferromagnetic (AF) modulus, the bulk ferrimagnetic exchange stiffness constant, and the AF exchange stiffness constant across the APB of strontium ferromolybdate are estimated. This is done by analyzing carefully selected experimental data of the magnetoresistance (MR). The boundary width and boundary energy are calculated by means of Kittel's theory of the structure of ferromagnetic domains in films and small particles. The evaluation of these parameters deepens the understanding of MR in strontium ferromolybdate ceramic and thin‐film samples possessing a high density of APBs. [ABSTRACT FROM AUTHOR]

A ferroelectric domain-enhanced electron emission mechanism is presented. Findings reveal that the motion of 90 degree domain walls resulted in a significant enhancement in the electron emission from thin ferroelectric thin film excited by ac fields with amplitudes near the coercive field.

Herein, for the first time, a model is developed for the description of magnetoresistance in nanosized, granular Sr2FeMoO6–δ–SrMoO4 core–shell structures, which is based on the fluctuation‐induced tunneling model. Parameters of the fluctuation‐induced tunneling model of granular materials are calculated. The magnetic field is considered to affect the tunneling barrier height. The linear and quadratic coefficients of this effect are estimated. [ABSTRACT FROM AUTHOR]