Fabrication and magnetic control of Y3Fe5O12 cantilevers

Abstract

We have fabricated ferrite cantilevers in which their vibrational properties can be controlled by external magnetic fields. Submicron-scale cantilever structures were made from Y3Fe5O12 (YIG) films by physical etching combined with use of a focused ion beam milling technique. We found that the cantilevers exhibit two resonance modes which correspond to horizontal and vertical vibrations. Under external magnetic fields, the resonance frequency of the horizontal mode increases, while that of the vertical mode decreases, quantitatively consistent with our numerical simulation for magnetic forces. The changes in resonance frequencies with magnetic fields reach a few percent, showing that efficient magnetic control of resonance frequencies was achieved.Spin mechanics [1], which explores interplay between magnetism and mechanical motion, is a young research field emerging along with the advance in spintronics [2]. Classical examples of such phenomena are the Einsteinde Haas effect [3] and its inverse effect, the Barnett effect [4]. In the Einstein-de Haas effect, mechanical rotation is induced by transfer of angular momentum from magnetization to mechanical ones. To detect mechanical effects induced by spins, a cantilever structure provides one of the most suitable tools [5][6][7][8][9][10]. A cantilever is a long rigid plate of which one end is supported tightly but the other end can mount a load. Because of their high sensitivity [11,12], cheapness, and ease of fabrication in large areas, cantilever structures have been essential in spin mechanics [1,[5][6][7][8][9][10].In commercial devices e.g. micro-electro-mechanical systems (MEMS), cantilevers are mostly fabricated on silicon wafers. Silicon is the most common semiconducting material on the earth, and widely used as a base material in the semiconductor industry. Silicon cantilevers thereby have great advantage since nanofabrication techniques developed in the semiconductor industry can be harnessed effectively. However, recent development in state-of-the-art nanofabrication techniques such as a focused ion beam (FIB) method enables wide material choice as ingredients of cantilevers, such as magnetic, piezoelectric, and ferroelectric materials. Cantilevers made of such functional materials are promising for exploration of new features in minute cantilever devices.In this study, we have fabricated ferrimagnetic cantilevers using garnet ferrite Y 3 Fe 5 O 12 (YIG). YIG is a typical magnetic insulator [13][14][15][16][17][18] with excellent microwave properties, and thus has widely been used in magnonics and spintronics fields [2]. However, direct fabrication of YIG cantilevers has not been reported yet, * Electronic address: seo@imr.tohoku.ac.jp although magnetic control of cantilever properties is expected owing to the strong spontaneous magnetization of YIG. In addition to functionality as magnetic cantilevers, a marriage between MEMS technology and spintronics will acceralate the study of spin mechanics. As shown in the following, we successfully fabricated a Y...

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