Spin-Wave Spectrum in `Single-Domain' Magnetic Ground State of Triangular Lattice Antiferromagnet CuFeO2
Spin-Wave Spectrum in `Single-Domain' Magnetic Ground State of Triangular Lattice Antiferromagnet CuFeO2
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三角晶格反铁磁体 CuFeO2 的“单域”磁基态自旋波谱
DOI：
10.1143/jpsj.80.014714
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
N. Terada
中科院分区：
文献类型：
--
作者：
T. Nakajima;S. Mitsuda;T. Haku;K. Shibata;K. Yoshitomi;Y. Noda;N. Aso;Y. Uwatoko;N. Terada
通过中子散射测量，我们研究了三角形晶格反铁磁体CuFeO2共线四亚晶格（4SL）磁基态中的自旋波激发。CuFeO2最近被认为是强受挫磁体、自旋晶格耦合系统和多铁性磁体。为了避免来自三个不同方向的磁畴的自旋波谱的混合，反映了晶体结构的三角对称性，我们在单晶CuFeO2的[1-10]方向上施加了单轴压力。通过弹性中子散射测量，我们发现仅在10mpa的单轴压力下，4SL相几乎处于“单畴”状态。因此，我们使用单畴样品进行了非弹性中子散射测量，并确定了两个不同的自旋波分支。上自旋波分支的色散关系不能用先前的理论模型来解释[R]。S. Fishman: J. applel。物理学报，2008,(3):798 - 798。这意味着晶格自由度在该系统中自旋波激发中的重要性，因为先前的计算忽略了自旋驱动的4SL相晶格畸变的影响。我们还讨论了目前的结果与最近发现的“电磁子”激发之间的关系。
By means of neutron scattering measurements, we have investigated spin-wave excitation in a collinear four-sublattice (4SL) magnetic ground state of a triangular lattice antiferromagnet CuFeO2, which has been of recent interest as a strongly frustrated magnet, a spin-lattice coupled system and a multiferroic. To avoid mixing of spin-wave spectrum from magnetic domains having three different orientations reflecting trigonal symmetry of the crystal structure, we have applied uniaxial pressure on [1-10] direction of a single crystal CuFeO2. By elastic neutron scattering measurements, we have found that only 10 MPa of the uniaxial pressure results in almost 'single domain' state in the 4SL phase. We have thus performed inelastic neutron scattering measurements using the single domain sample, and have identified two distinct spin- wave branches. The dispersion relation of the upper spin-wave branch cannot be explained by the previous theoretical model [R. S. Fishman: J. Appl. Phys. 103 (2008) 07B109]. This implies the importance of the lattice degree of freedom in the spin-wave excitation in this system, because the previous calculation neglected the effect of the spin-driven lattice distortion in the 4SL phase. We have also discussed relationship between the present results and the recently discovered "electromagnon" excitation.