Electrical Probing of Magnetic Phase Transition and Domain Wall Motion in Single-Crystalline Mn5Ge3 Nanowire

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• 作者：Jianshi Tang ; Chiu-Yen Wang ; Wanjun Jiang ; Li-Te Chang ; Yabin Fan ; Michael Chan ; Can Wu ; Min-Hsiu Hung ; Pei-Hsuan Liu ; Hong-Jie Yang ; Hsing-Yu Tuan ; Lih-Juann Chen ; Kang L. Wang
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：December 12, 2012
• 年：2012
• 卷：12
• 期：12
• 页码：6372-6379
• 全文大小：452K
• 年卷期：v.12,no.12(December 12, 2012)
• ISSN：1530-6992

文摘

In this Letter, the magnetic phase transition and domain wall motion in a single-crystalline Mn₅Ge₃ nanowire were investigated by temperature-dependent magneto-transport measurements. The ferromagnetic Mn₅Ge₃ nanowire was fabricated by fully germaniding a single-crystalline Ge nanowire through the solid-state reaction with Mn contacts upon thermal annealing at 450 掳C. Temperature-dependent four-probe resistance measurements on the Mn₅Ge₃ nanowire showed a clear slope change near 300 K accompanied by a magnetic phase transition from ferromagnetism to paramagnetism. The transition temperature was able to be controlled by both axial and radial magnetic fields as the external magnetic field helped maintain the magnetization aligned in the Mn₅Ge₃ nanowire. Near the magnetic phase transition, the critical behavior in the 1D system was characterized by a power-law relation with a critical exponent of 伪 = 0.07 卤 0.01. Besides, another interesting feature was revealed as a cusp at about 67 K in the first-order derivative of the nanowire resistance, which was attributed to a possible magnetic transition between two noncollinear and collinear ferromagnetic states in the Mn₅Ge₃ lattice. Furthermore, temperature-dependent magneto-transport measurements demonstrated a hysteretic, symmetric, and stepwise axial magnetoresistance of the Mn₅Ge₃ nanowire. The interesting features of abrupt jumps indicated the presence of multiple domain walls in the Mn₅Ge₃ nanowire and the annihilation of domain walls driven by the magnetic field. The Kurkij盲rvi model was used to describe the domain wall depinning as thermally assisted escape from a single energy barrier, and the fitting on the temperature-dependent depinning magnetic fields yielded an energy barrier of 0.166 eV.

Keywords:

Ferromagnetic nanowire; Mn₅Ge₃; magnetic phase transition; domain wall motion; critical behavior