The thin film rare earth magnet and manufacturing method thereof

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This invention provides a thin-film rare earth magnet that has significantly increased magnetic coercive force while suppressing a lowering in residual magnetization of the thin-film magnet. This magnet is a 1 µm to 300 µm-thick thin-film magnet manufactured by heat treating a laminated structure having a multilayer structure. In this structure, an M or M alloy layer, wherein M represents one or at least two of Pr, Dy, Tb and Ho, and a 0.05 µm to 50 µm-thick Nd-Fe-B-base alloy layer have been alternately stacked on top of each other to form a multilayer structure of three or more layers. Upon the heat treatment, the M or M alloy component and the Nd-Fe-B-base alloy component have been mutually diffused. Further, upon the heat treatment, an (Nd, M)2Fe14B crystal is formed on the surface part of Nd2Fe14B crystal grains. The (Nd, M)2Fe14B crystal has been produced as a result of replacement of Nd with element M and dissolution of the replaced Nd in solid solution. Further, a crystal grain boundary phase of M or M alloy is formed in the boundary of Nd2Fe14B crystal grains so that the interface of the M or M alloy phase is in contact with the (Nd, M)2Fe14B crystal.