Room-temperature coexistence of large electric polarization and magnetic order in BiFeO3 single crystals
Room-temperature coexistence of large electric polarization and magnetic order in BiFeO3 single crystals
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DOI：
10.1103/physrevb.76.024116
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发表时间：
2007-07-01
影响因子：
3.7
通讯作者：
Fusil, S.
中科院分区：
文献类型：
--
作者：
Lebeugle, D.;Colson, D.;Fusil, S.
从实验的角度来看，BiFeO 3的室温铁电性提出了许多问题。对BiFeO_3与Pb（Ti，Zr）O_3固溶体的电学测量表明，在居里温度T_C =1143 K以下，BiFeO_3存在自发极化。然而，在大多数报道的工作中，合成的样品在室温下太导电，在没有任何外在物理或化学参数的影响的情况下，在本体中获得清晰的极化回路。令人惊讶的是，到目前为止，还没有报道的P（E）（极化与电场）环在室温下的BiFeO 3单晶。我们在这里描述我们的程序合成陶瓷和生长质量好的大尺寸单晶的助熔剂法。我们证明BiFeO 3确实是铁电体在室温下，通过证据，由piezoresponse力显微镜和P（E）环。发现极化很大，约为60 μ C/cm（2），这是一个只有在薄膜中才能达到的值。还介绍了利用超导量子干涉仪磁强计和穆斯堡尔谱进行的磁测量。后者证实了核磁共振测量的结果有关的各向异性的超精细领域归因于磁摆线结构。
From an experimental point of view, room-temperature ferroelectricity in BiFeO3 is raising many questions. Electric measurements made a long time ago on solid solutions of BiFeO3 with Pb(Ti,Zr)O-3 indicate that a spontaneous electric polarization exists in BiFeO3 below the Curie temperature T-C=1143 K. Yet in most reported works, the synthesized samples are too conductive at room temperature to get a clear polarization loop in the bulk without any effects of extrinsic physical or chemical parameters. Surprisingly, up to now there has been no report of a P(E) (polarization versus electric field) loop at room temperature on single crystals of BiFeO3. We describe here our procedure to synthesize ceramics and to grow good quality sizeable single crystals by a flux method. We demonstrate that BiFeO3 is indeed ferroelectric at room temperature through evidence by piezoresponse force microscopy and P(E) loops. The polarization is found to be large, around 60 mu C/cm(2), a value that has only been reached in thin films. Magnetic measurements using a superconducting quantum interference device magnetometer and Mossbauer spectroscopy are also presented. The latter confirms the results of nuclear magnetic resonance measurements concerning the anisotropy of the hyperfine field attributed to the magnetic cycloidal structure.