铁磁金属薄膜磁性的电场调制

Magnetism in thin-film ferromagnets modified by an electric field

文章主要介绍了Science上发表的Weisheit M等人利用外加电场调制铁磁金属薄膜磁性的实验工作.该工作所用的实验方法简单、有效,为人们改变金属磁性开辟了一条崭新的道路.有序合金FePt和FePd具有垂直的磁晶各向异性,将它们置入碳酸丙烯脂的电解液中,利用铁磁薄膜和液体接触面形成的双电层电容结构,可以在样品表面产生很大的电场,从而可以调控金属薄膜费米面附近未成对的d电子的态密度.由于费米面附近电子填充数的变化,铁磁薄膜的磁晶各向异性也会受到调制.实验结果表明,-0.6mV的电压变化会导致厚度为2nm的FePt和FePd合金的矫顽力分别减少4.5%和增加1%.这是第一次观测到电场调控金属薄膜磁性的实验工作.

We describe an experiment in which the nfagnetism of a ferromagnetic thin-film is modified with an external electric field. The magnetocrystalline anisotropy of ordered FePt （FePd） compounds which have perpendicular magnetocrystalline anisotropy can be modified by an applied electric field when immersed in an electrolyte. The modification of the magnetic parameters is attributed to a change in the number of unpaired d electrons in response to the large electric field because of the formation of an electrolytic double layer in front of the ferromagnetic thin-film. The experimental results demonstrated that a voltage change of -0.6 volts on a 2 nm thick film altered the coercivity by 4.5% and ＋ 1% in FePt and FePd, respectively. This is the first experimental observation of the modification of the magnetism in thin-film ferromagnets by an electric field.