Oxide interface displaying electronically controllable ferromagnetism

A method of controlling an electronically controllable ferromagnetic oxide structure, the electronically controllable ferromagnetic oxide structure comprising:

• (a) a first layer in contact with a second layer, wherein the second layer has a thickness of at least about 4 unit cells, the thickness being in a direction substantially perpendicular to an interface between the first and the second layers, wherein the interface is defined by a plane between the first and second layers;
• and
• (b) at least one surface electrode and at least one interfacial contact, the at least one surface electrode and the at least one interfacial contact being in contact with at least one of the first layer or the second layer, wherein:
• (i) the at least one surface electrode and the at least one interfacial contact are configured to alter the charge carrier density at the interface between the first and second layers,
• (ii) the at least one surface electrode is deposited on the second layer on a surface spaced from the interface, and the at least one interfacial contact extends from the surface spaced from the interface through the second layer to the interface, and
• (iii) the interface between the first and the second layers is configured to exhibit electronically controlled ferromagnetism in response to alteration of the charge carrier density,
• the method comprising:
• (1) applying a positive voltage to the at least one surface electrode;
• (2) applying a magnetic field to the electronically controllable ferromagnetic oxide structure;
• and
• (3) switching the positive voltage applied to the at least one surface electrode to a negative voltage so as to cause the interface to switch between a ferromagnetic state and a non-ferromagnetic state.

A method of altering a ferromagnetic state at an interface of a multi-layered oxide structure comprising at least a first layer and a second layer, the method comprising:

• establishing a voltage difference between the interface and a material in contact with at least one of the layers of the multi-layered oxide structure, the interface being between the first and second layers of the oxide structure and defined by a plane between the first and second layers, wherein:
• (a) the voltage difference is sufficient to alter a charge carrier density at the interface between the first and second layers of the oxide structure;
• (b) the second layer has a thickness in a direction substantially perpendicular to the interface between the first and second layers;
• (c) the oxide structure further comprises at least one surface electrode and at least one interfacial contact, the at least one surface electrode and the at least one interfacial contact being in contact with at least one of the first layer or the second layer, and
• (d) the interface between the first and second layers of the oxide structure is capable of exhibiting electronically controlled ferromagnetism,
• wherein the at least one surface electrode is deposited on the second layer on a surface spaced from the interface, and the at least one interfacial contact extends from the surface spaced from the interface through the second layer to the interface.