Spin-glass behaviors in carrier polarity controlled Fe3-xTixO4 semiconductor thin film
Spin-glass behaviors in carrier polarity controlled Fe3-xTixO4 semiconductor thin film
复制标题
载流子极性控制的 Fe3-xTixO4 半导体薄膜中的自旋玻璃行为
DOI：
10.1063/1.4928408
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
H. Kumigashira and H. Tabata
中科院分区：
文献类型：
--
作者：
H. Yamahara;M. Seki;M. Adachi;M. Takahashi;H. Nasu;K. Horiba;H. Kumigashira and H. Tabata
为了利用自旋玻璃的记忆功能来设计基本的磁性半导体元件，研究了自旋玻璃(团簇自旋玻璃)的载流子类型控制。磁铁矿中载流子极性控制的一个关键是通过Ti(IV)取代实现Fe(II)和Fe(III)之间的价态工程。采用脉冲激光沉积法在尖晶石−衬底上制备了(0 0 1)取向的Fe{sub3 Sub2}OSub4}薄膜。热电功率测量表明，富钛薄膜(x = 0.8)表现为p型导电，而贫钛薄膜(x = 0.6-0.75)表现为n型导电。X射线吸收光谱证实了八面体亚晶格中Fe(III)还原为Fe(II)，然后进行了Ti(IV)置换的系统过程。所有的Fe{sub3−x}Ti{subx}O{sub4}薄膜(x = 0.6-0.8)在室温以上都表现出亚铁磁性。其次，研究了富钛Fe{sub2.2}Ti{sub0.8}O{sub4}薄膜的自旋玻璃行为，因为这种磁稀释系统有望表现出自旋玻璃行为。富钛Fe{sub2.2}Ti{sub0.8}O{sub4}薄膜的直流磁化强度和交流磁化率测量表明，存在自旋玻璃相。观察到了热和磁场历史记忆效应，并将其归因于剩余磁化的长时间衰减特性。对随时间变化的热剩余磁化强度的详细分析揭示了团簇自旋玻璃态的存在。
Carrier-type control of spin-glass (cluster spin-glass) is studied in order to engineer basic magnetic semiconductor elements using the memory functions of spin-glass. A key of carrier-polarity control in magnetite is the valence engineering between Fe(II) and Fe(III) that is achieved by Ti(IV) substitution. Single phases of (001)-oriented Fe{sub 3−x}Ti{sub x}O{sub 4} thin films have been obtained on spinel MgAl{sub 2}O{sub 4} substrates by pulsed laser deposition. Thermoelectric power measurements reveal that Ti-rich films (x = 0.8) show p-type conduction, while Ti-poor films (x = 0.6–0.75) show n-type conduction. The systematic Fe(III) reduction to Fe(II) followed by Ti(IV) substitution in the octahedral sublattice is confirmed by the X-ray absorption spectra. All of the Fe{sub 3−x}Ti{sub x}O{sub 4} films (x = 0.6–0.8) exhibit ferrimagnetism above room temperature. Next, the spin-glass behaviors of Ti-rich Fe{sub 2.2}Ti{sub 0.8}O{sub 4} film are studied, since this magnetically diluted system is expected to exhibit the spin-glass behaviors. The DC magnetization and AC susceptibility measurements for the Ti-rich Fe{sub 2.2}Ti{sub 0.8}O{sub 4} film reveal the presence of the spin glass phase. Thermal- and magnetic-field-history memory effects are observed and are attributed to the long time-decay nature of remanent magnetization. The detailed analysis of the time-dependent thermoremanent magnetization reveals the presence of the cluster spin glass state.