A mechanical rotatable magnetic force microscope operated in a 7 T superconducting magnet

We present a mechanical rotatable magnetic force microscope (MFM) with precise angle control that can be operated in a 7 T superconducting magnet. An inertial piezoelectric motor called a SpiderDrive was used for the coarse approach because of its high compactness, high rigidity, and small size. Due to the mechanical rotation design, the MFM head can be rotated in a 7 T superconducting magnet with a bore size of 89 mm so that the direction of the magnetic field can be changed from 0° to 90° continuously. The highest in-plane magnetic field strength tested was 7 T. This is the first rotatable MFM ever reported. Using the homemade rotatable MFM, we investigated a 40 nm thick La0.67Ca0.33MnO3 (LCMO) thin film on NdGaO3 (100) substrate with anisotropy, determining that the charge-ordering insulating (COI) phase of the LCMO disappears as the direction of the magnetic field changed from 0° to 90°. Furthermore, the ferromagnetic pattern, appearing as bright and dark contrasts and similar to that formed by the S and N of a magnet, was seen parallel to the direction of the magnetic field. The rotatable MFM in this paper is expected to be widely used in studying the anisotropy of magnetic materials.

本文报道了一款可在7 T超导磁体中运行、具备精确角度调控能力的机械可旋转磁力显微镜（MFM）。鉴于一款名为蜘蛛驱动器（SpiderDrive）的惯性压电电机具备结构紧凑、刚度优异且体积小巧的优势，本装置采用其实现粗调进给。得益于机械旋转设计，该MFM探头可在孔径为89 mm的7 T超导磁体中完成旋转，使磁场方向可在0°至90°范围内连续可调，实测最高面内磁场强度可达7 T。本装置为迄今首台可旋转式MFM。利用自研的可旋转MFM，我们对生长于NdGaO₃(100)衬底上的40 nm厚La₀.₆₇Ca₀.₃₃MnO₃（LCMO）各向异性薄膜展开研究，发现当磁场方向从0°偏转至90°时，LCMO的电荷有序绝缘（COI）相消失。此外，我们还观测到与磁场方向平行的铁磁畴图案，其呈现出类似磁铁南北极所形成的明暗衬度。本研究开发的可旋转MFM有望在磁性材料各向异性研究中得到广泛应用。