Electric control of room temperature ferromagnetism in a Pb(Zr0.2Ti0.8)O3∕La0.85Ba0.15MnO3 field-effect transistor

Abstract

Spintronics, which takes advantage of both spin and charge degrees of freedom, is a promising key technique relevant to future applications of information and data storage. Ferromagnetic transition metal oxides, including perovskite manganites, represent the most promising materials for use as devices controlling magnetic states by an electric field at high temperature with high efficiency. This is because these materials possess a strong intrinsic relationship between charge and magnetism, showing ferromagnetism above room temperature by adjustment of carrier filling, in addition, particular magnetoelectric properties such as a colossal magnetoresistance phenomenon. Nevertheless, the device operation such a field control of magnetism has not been verified so far in manganites. It is essential to determine whether the magnetism of manganites can be controlled via carriers modulated by an electric field in these applications. Here the authors report on the direct demonstration of a simultaneous change in the magnetic and electric-transport properties in a ferromagnetic oxide field-effect transistor. A working temperature above 293K was achieved. This result should facilitate the use of spintronic devices in strongly correlated 3d-electron systems working at practical temperatures.

Magnetoelectric Effects in Complex Oxides with Competing Ground States

“…[14] In region II, the opposite behavior is observed, as expected from the higher T c for the accumulation state. [15,18] Analysis of the magnetization data of Figure 2 reveals that the two M-T curves collapse onto each other after a suitable vertical rescaling and a temperature shift of 20 K. This result shows that, while there is a substantial change in T c and saturation magnetization for the accumulation and depletion states, the normalized M-T behavior is largely unaffected by the change in carrier concentration. The critical temperatures are estimated as 179 and 197 K for the depletion and accumulation states, respectively, from linear extrapolations to zero magnetization near the critical region (Fig.…”

Materials science: Enter the oxides

“…Indeed, says Tokura, "the route via thin films offers the most straightforward fabrication method to realize a multiferroic material". As well as looking at the coupling of two different properties at an oxide interface, researchers are looking for applications in which a single property, such as magnetic field 7,8 or electrical conductivity, is controllably turned on and off. "Controlling conductivity as a whole, rather than electrical current itself, in some sense is the most exciting area, " says Stuart Parkin, a physicist at IBM's Almaden Research Center in San Jose, California.…”

Ferroelectric Field Effect Control of Magnetism in Multiferroic Heterostructures

“…This result indicates that the properties of the bottom interface, characterized by the presence of an electric and magnetically "dead layer," is less amenable to field modulation. For the PZT/LBMO device structures Kanki et al (2006), a change in the magnetic hysteresis loops is observed as the PZT polarization is switched, with the magnetic signal decreasing when going from the accumulation to the depletion state, a trend opposite to that found in the PZT/LSMO system Molegraaf et al (2009) Duan et al (2006); the magnetoelectric effect in both these systems is attributed to changes in the bonding length of the Fe cations as a function of the direction of the ferroelectric polarization, giving rise to large changes in the magnetic moment of Fe. A magnetoelectric coupling based on charge screening and in the enhancement of the spin imbalance at the Fermi level has been studied in a symmetric SrTiO 3 /SrRuO 3 /SrTiO 3 structure, where the spin imbalance is described in terms of a spin capacitor effect, with the spin asymmetry stored at the interfaces in a fashion similar to that of charge in a normal capacitor Rondinelli et al (2008).…”