Electric field control of domain wall propagation in Pt/Co/GdOx films

Abstract

The influence of a gate voltage on domain wall (DW) propagation is investigated in ultrathin Pt/Co/gadolinium oxide (GdOx) films with perpendicular magnetic anisotropy. The DW propagation field can be enhanced or retarded by an electric field at the Co/GdOx interface and scales linearly with gate voltage up to moderate bias levels. Higher gate voltage levels, corresponding to electric fields >0.2 V/nm, produce a large irreversible change to the magnetic anisotropy that can enable nonvolatile switching of the coercivity. V

Electric-field control of domain wall nucleation and pinning in a metallic ferromagnet

“…Despite the limited penetration depth of an E-field in metals, the charge induced at the metal/dielectric interface on the topmost atomic layers is sufficient to modify the surface magnetic anisotropy energy (MAE) by a non negligible amount in ultrathin ferromagnetic layers as suggested by electronic structure calculations [9][10][11] . This has a particular impact in systems where the different anisotropy contributions almost cancel each other out, resulting in a large relative variation of the total effective MAE when the surface contribution is modified with the voltage [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] . We have studied here a Pt/Co/AlOx sample where the surface MAE could be varied in two ways : charging the metal/dielectric interface and modifying its oxidation.…”

Voltage-gated pinning in a magnetic domain-wall conduit

“…11,13 This has been demonstrated to be of use in exciting applications such as low-dissipative voltage-driven switching, 14,15 voltage-gated switching by the Spin Hall effect, 16 controlling the domain structure, [17][18][19] and control over magnetic domain-wall (DW) velocities. [20][21][22][23][24] Several mechanisms can be responsible for these effects: strain transfer from a ferroelectric layer, [17][18][19] changes to the occupation of electron orbitals at the FM/oxide interface, 1 charge trapping, 25 and finally, migration of O ions from the interface. 26 Recently, Bauer et al 26 have been able to create pinning sites in a DW conduit which can be reprogrammed by applying a voltage.…”

Large time-dependent coercivity and resistivity modification under sustained voltage application in a Pt/Co/AlOx/Pt junction

“…A viable candidate for such a process is the electromigration of oxygen vacancy defects in the dielectric. This mechanism has been suggested to occur in similar devices, 4,7,8,11 and was confirmed to affect the perpendicular magnetic anisotropy at Fe/MgO interfaces. 11 Moreover, electromigration of oxygen vacancies is known to occur in amorphous AlOx barriers, 15 causing soft dielectric breakdown at high electric fields, similar to the behavior observed in Figure 3(c).…”

“…Using a Pt/Co/GdOx/Au system, Bauer et al 4 demonstrated a large coercivity and resistivity modification close to the hard dielectric breakdown voltage. They identified migration of oxygen vacancies and charge trapping in the GdOx layer as possibly relevant physical mechanisms.…”

“…The modification of magnetic anisotropy by application of electric fields across magnet-insulator interfaces has been experimentally observed in a variety of systems. [1][2][3][4][5] This method of magnetization control has enormous potential for spintronics applications, as the power consumption can be orders of magnitude lower than in current-based devices. 6 The magnitude, symmetry, and timescale of the observed effect differ significantly between experiments, suggesting that physics beyond the charging of an ideal capacitor play a role.…”