Giant negative magnetoresistance of spin polarons in magnetic semiconductors–chromium-doped Ti2O3 thin films

Abstract

Epitaxial Cr-doped Ti2O3 films show giant negative magnetoresistance up to −365% at 2K. The resistivity of the doped samples follows the behavior expected of spin (magnetic) polarons at low temperature. Namely, ρ=ρ0exp(T0∕T)p, where p=0.5 in zero field. A large applied field quenches the spin polarons and p is reduced to 0.25 expected for lattice polarons. The formation of spin polarons is an indication of strong exchange coupling between the magnetic ions and holes in the system.

Coexistence of exchange-bias fields and vertical magnetization shifts in ZnCoO∕NiO system

“…3, both ⌬M and H ex increased with increasing the cooling field. The complex spin ground state of DMS was reported, 11 which may result in the formation of SGL phases. When the FC field is larger than 500 Oe, a linear dependence of H ex on ⌬M was observed, shown in Fig.…”

Structure, optical, and magnetic properties of sputtered manganese and nitrogen-codoped ZnO films

“…[19][20][21] According to Curie-Weiss law, a negative Curie temperature ͑ = −47 K͒ was obtained by extrapolating, suggesting an antiferromagnetic ground state for the system. 19,20 Ferromagnetic hysteresis shrinks with increasing temperature and the negative Curie temperature illustrate a dominant competition between ferromagnetic and antiferromagnetic states, which leads to a complex temperature dependence of field-cooled magnetization as reported by Wang et al 20 ZnO is generally in n type due to shallow donors associated with low-energy native point defects, such as oxygen vacancies ͑V O ͒ and Zn interstitials ͑Zn i ͒. Even if an active N 2 plasma is used, it is still difficult to achieve high hole densities due to the compensation by O vacancies, N O -Zn O or N O -͑N 2 ͒ O complexes.…”

Memristor PUF—A Security Primitive: Theory and Experiment

“…In order to calculate the total current through memristor, the concentration of oxygen vacancies needs to be known through experimental X-ray diffraction (XRD) and transmission electron microscope (TEM) studies [34].…”