Voltage-induced reversible changes in the magnetic coercivity of Fe/ZnO heterostructures

Abstract

In this study, the magnetic coercivity (Hc) of Fe/ZnO heterostructure monotonically decreased as voltage was applied. The reversibility of this effect was demonstrated by cyclically changing the bias voltage from 0 to 6–9 V; the Hc decreased 15%–20%. The Hc value exhibited the same variation whether the applied voltage was positive or negative. As thick Fe-oxide gradually formed at the interface by using direct current heating, the Hc increased and the Fe/ZnO heterostructure demonstrated a similar voltage-induced reduction of Hc.

Visualizing hydrogen diffusion in magnetic film through magneto-optical Kerr effect

“…A 100-nm-thick ZnO film was subsequently deposited on part of the Co 25 Pd 75 film, leaving one end of Co 25 Pd 75 stripe bared. The ZnO film was prepared at room temperature in an oxygen ambient pressure of 8.0 Pa through pulsed-laser deposition 31 . A Nd:YAG Q-switch laser provided a laser wavelength of 266 nm with an energy density of approximately 2.7 J/cm 231,32 .…”

Quantum-well-induced engineering of magnetocrystalline anisotropy in ferromagnetic films

“…So far it has been measured that the MAE magnitude changes remarkably (around 40%) by tuning applied voltage to inject charges on a Fe film. 13,22,23 Our results explain the microscopic origin, show that the MAE of a Fe film can be boosted by several times and hence the magnetization orientation can be switched by injecting charges to shift the QWSs near E F .…”

“…[19][20][21] Besides, the value of MAE is measured to increase remarkably by applying a small electric field to charge a Fe film moderately. 13 Such property has great application potential as it persists to a Fe film thicker than 1 nm, 22,23 even though the field is strongly screened in such a thick film. A recent experiment reveals a link between this property and QWSs, 22 but the detailed mechanism remains a puzzle.…”

Modulation of magnetic coercivity in Ni thin films by reversible control of strain

“…Accordingly, many studies have been carried out at the aim of electric field control of magnetism in the last decade. Up to now, several kinds of device structure have been proposed and demonstrated, for example the utilization of single magnetic layer on oxide [3][4][5][6][7][8][9][10][11][12][13], magnetic semiconductors [14][15][16][17][18][19], multiferroic materials [20], and other hybrid systems [4,20]. These reports proposed various physical mechanism for the electricfield-control of magnetism as follows: the modulation of carrier density, d-state electron occupation-induced change of interface magnetic anisotropy [21], and the coupling between ferroelectricity and ferromagnetism.…”

“…However, the voltage control of magnetic semiconductors is not typically applicable in ambient conditions because of the low Curie temperature. Besides, numerous recent studies have focused on ferromagnetic transition metals combined with oxide thin films, such as MgO [3][4][5][6][7][8][9][10][11], AlO x [9] and ZnO [12,13], in which the interface charge accumulation may modulate the interface magnetic anisotropy and thus changes the magnetic behavior. However, this interface effect can be applied only to thin films of limited thickness in which the interface magnetic anisotropy dominates the magnetic behavior.…”