Long-Range Magnetic Order in Mn[N(CN)2]2(pyz) {pyz = pyrazine}. Susceptibility, Magnetization, Specific Heat, and Neutron Diffraction Measurements and Electronic Structure Calcul
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- 作者：Jamie L. Manson ; Qing-zhen Huang ; Jeffrey W. Lynn ; Hyun-Joo Koo ; Myung-Hwan Whangbo ; Rodney Bateman ; Takeo Otsuka ; Nobuo Wada ; Dimitri N. Argyriou ; and Joel S. Miller
- 刊名：Journal of the American Chemical Society
- 出版年：2001
- 出版时间：January 10, 2001
- 年：2001
- 卷：123
- 期：1
- 页码：162 - 172
- 全文大小：171K
- 年卷期：v.123,no.1(January 10, 2001)
- ISSN：1520-5126
文摘
Using dc magnetization, ac susceptibility, specific heat, and neutron diffraction, we have studiedthe magnetic properties of Mn[N(CN)2]2(pyz) {pyz = pyrazine} in detail. The material crystallizes in themonoclinic space group P21/n with a = 7.3248(2), b = 16.7369(4), and c = 8.7905 (2) Å, 
= 89.596 (2)
,V = 1077.65(7) Å3, and Z = 4, as determined by Rietveld refinement of neutron powder diffraction data at1.35 K. The 5 K neutron powder diffraction data reflect very little variation in the crystal structure.Interpenetrating ReO3-like networks are formed from axially elongated Mn2+ octahedra and edges made up of
-bonded [N(CN)2]- anions and neutral pyz ligands. A three-dimensional antiferromagnetic ordering occursbelow TN = 2.53(2) K. The magnetic unit cell is double the nuclear one along the a- and c-axes, giving the(1/2, 0, 1/2) superstructure. The crystallographic and antiferromagnetic structures are commensurate and consistof collinear Mn2+ moments, each with a magnitude of 4.15(6) B aligned parallel to the a-direction (Mn-pyz-Mn chains). Electronic structure calculations indicate that the exchange interaction is much strongeralong the Mn-pyz-Mn chain axis than along the Mn-NCNCN-Mn axes by a factor of approximately 40,giving rise to a predominantly one-dimensional magnetic system. Thus, the variable-temperature magneticsusceptibility data are well described by a Heisenberg antiferromagnetic chain model, giving g = 2.01(1) andJ/kB = -0.27(1) K. Owing to single-ion anisotropy of the Mn2+ ion, field-induced phenomena ascribed tospin-flop and paramagnetic transitions are observed at 0.43 and 2.83 T, respectively.
= 89.596 (2),V = 1077.65(7) Å3, and Z = 4, as determined by Rietveld refinement of neutron powder diffraction data at1.35 K. The 5 K neutron powder diffraction data reflect very little variation in the crystal structure.Interpenetrating ReO3-like networks are formed from axially elongated Mn2+ octahedra and edges made up of-bonded [N(CN)2]- anions and neutral pyz ligands. A three-dimensional antiferromagnetic ordering occursbelow TN = 2.53(2) K. The magnetic unit cell is double the nuclear one along the a- and c-axes, giving the(1/2, 0, 1/2) superstructure. The crystallographic and antiferromagnetic structures are commensurate and consistof collinear Mn2+ moments, each with a magnitude of 4.15(6) B aligned parallel to the a-direction (Mn-pyz-Mn chains). Electronic structure calculations indicate that the exchange interaction is much strongeralong the Mn-pyz-Mn chain axis than along the Mn-NCNCN-Mn axes by a factor of approximately 40,giving rise to a predominantly one-dimensional magnetic system. Thus, the variable-temperature magneticsusceptibility data are well described by a Heisenberg antiferromagnetic chain model, giving g = 2.01(1) andJ/kB = -0.27(1) K. Owing to single-ion anisotropy of the Mn2+ ion, field-induced phenomena ascribed tospin-flop and paramagnetic transitions are observed at 0.43 and 2.83 T, respectively.