Orbital ordering and magnetism of fluoride and chloride compounds at high pressures

高压下氟化物和氯化物的轨道有序性和磁性

• 批准号: 08454088
• 负责人: YAMADA Isao
• 金额: $ 5.06万
• 依托单位: Chiba University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454088/
• 关键词: orbital ordering; fluoride compound; chloride compound; high pressure; 弗化物磁性体; 反強磁性的軌道整列; 強磁性的軌道整列; 高圧; 磁化率

Although the layred compounds K_2CuF_4 and La_2CuO_4 have a K_2NiF_4-type crystal structure, the former is a ferromagnet while the latter is an antiferromagnet. Such a difference of magnetism is due to the antiferrodistortive and ferrodistortive orbital orderings of 3d-holes, respectively. Under a high pressure, we expect that K_2CuF_4 turns into an antiferromagnet because of a change of orbital ordering from antiferrodistortive to ferrodistortive.From the magnetic susceptibility measurements at low temperatures under hydrostatic high pressures, we found a magnetic change from ferromagnetism to antiferromagnetis around 9 GPa. To confirm that this magnetic change was surely due to a change of orbital ordering, we performed X-ray diffraction and phonon-Raman scattering experiments under high pressures. As a result, we found that the crystal structure changed around 9 GPa. This structurql transition was found to bring about a change of orbital ordering from antifferrodistortive to ferrodistortive.

层状化合物K_2CuF_4和La_2CuO_4虽然具有K_2NiF_4型晶体结构，但前者是铁磁体，后者是反铁磁体。这种磁性的差异是由于3d空穴的反铁畸变和铁畸变轨道排序，分别。在高压下，由于K_2CuF_4的轨道序由反铁磁畸变转变为铁磁畸变，我们推测它将转变为反铁磁.在低温下的静高压磁化率测量中，我们发现在9GPa左右，K_2CuF_4的磁性由铁磁转变为反铁磁.为了证实这种磁性变化确实是由于轨道有序的变化，我们在高压下进行了X射线衍射和声子拉曼散射实验。结果，我们发现晶体结构在9GPa左右发生了变化。发现这种结构转变引起了从反铁畸变到铁畸变的轨道有序的变化。

项目成果

M.Ishizuka: "Pressure-induced structural phase transition in the 2-d Ferrcningrset K_2CuF_4" Phys.Rev.B. 57. 64-67 (1998)

M.Ishizuka：“二维 Ferrcningrset K_2CuF_4 中压力诱导的结构相变”Phys.Rev.B。

M.HAGIWARA: "Spin-Glass Freezing in the S=1 Antiferromangetic heisenberg Chain NiC_2O_4・2[(2-methylimidazole)_x(H_2O)_<1-x>]" Phys.Rev.B 55. 5615-5618 (1997)

M.HAGIWARA：“S=1 反铁磁海森堡链 NiC_2O_4·2[(2-甲基咪唑)_x(H_2O)_<1-x>] 中的自旋玻璃冻结”Phys.Rev.B 55. 5615-5618 (1997) ）

I.YAMADA: "A Possible Relationship between the Newly Found Crystal Structure of CuGeO_3 and its Anomalous Dependence of Magnetic Susceptibility and Lattice Parameters on Temperature" J.Mag.Mag.Materials. 177. (1998)

I.YAMADA：“新发现的 CuGeO_3 晶体结构与其磁化率和晶格参数对温度的异常依赖性之间的可能关系”J.Mag.Mag.Materials。

Hirotaka Manaka: "Phonon-Raman Scattering of K_2CuF_4 at High Pressures" Journal of the Physical Society of Japan. (発売予定).

Hirotaka Manaka：“K_2CuF_4 在高压下的声子拉曼散射”日本物理学会杂志（待发布）。

Mamoru Isizuka: "Structural Change of K_2CuF_4 at High Pressures" Journal of the Physical Society of Japan. (発売予定).

Mamoru Isizuka：“K_2CuF_4 在高压下的结构变化”，日本物理学会杂志（待发布）。