scholarly journals Nontrivial phase diagram for an elastic interaction model of spin crossover materials with antiferromagnetic-like short-range interactions

2017 ◽  
Vol 96 (14) ◽  
Author(s):  
Masamichi Nishino ◽  
Seiji Miyashita ◽  
Per Arne Rikvold
Keyword(s):  
Phase Diagram ◽  
Short Range ◽  
Spin Crossover ◽  
Interaction Model ◽  
Elastic Interaction

scholarly journals Critical temperature and correlation length of an elastic interaction model for spin-crossover materials

2012 ◽  
Vol 85 (5) ◽  
Author(s):  
Taro Nakada ◽  
Takashi Mori ◽  
Seiji Miyashita ◽  
Masamichi Nishino ◽  
Synge Todo ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Correlation Length ◽  
Spin Crossover ◽  
Interaction Model ◽  
Elastic Interaction

Structural phase transition to disorder low-temperature phase in [Fe(ptz)6](BF4)2 spin-crossover compounds

2012 ◽  
Vol 68 (1) ◽  
pp. 40-56 ◽  
Author(s):  
Joachim Kusz ◽  
Maciej Zubko ◽  
Reinhard B. Neder ◽  
Phillipp Gütlich
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Spin Crossover ◽  
Structural Phase ◽  
The Other ◽  
Special Technique ◽  
Temperature Phase ◽  
Disordered Phase ◽  
Novel Approach ◽  
Low Temperature Phase

In the spin-crossover compound [Fe(ptz)6](BF4)2 (where ptz=1-n-propyltetrazole) six different phases are observed. When a single crystal is slowly cooled from high temperatures to those below 125 K, the reflections broaden into diffuse maxima and split into two maxima along the c* direction [Kusz, Gütlich & Spiering (2004). Top. Curr. Chem. 234, 129–153]. As both maxima are broad along the c* direction, the short-range order exists only along the c direction and in the ab plane the structure remains long-range ordered. In this disordered phase additional satellite reflections appear. Upon heating above 135 K, the diffuse maxima return to their previous shape and this process is completely reversible. Rapidly cooled samples, on the other hand, do not show such splitting and the symmetry remains R\bar 3, despite a jump in lattice parameters. We use a special technique to analyse the disorder model of the slowly cooled samples, which consists of layered domains shifted in the hexagonal ab plane. The low-spin disordered phase was solved in a novel approach to accommodate the very unusual twinning and refined in the non-standard space group C\bar 1. In contrast to the ordered low-spin phase, the Fe ion is in a non-centrosymmetric coordination polyhedron and two of the six propyl groups change their conformation.

scholarly journals Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model

2019 ◽  
Vol 100 (14) ◽  
Author(s):  
V. I. Kuz'min ◽  
Yu. S. Orlov ◽  
A. E. Zarubin ◽  
T. M. Ovchinnikova ◽  
S. G. Ovchinnikov
Keyword(s):  
Heisenberg Model ◽  
Short Range ◽  
Short Range Order ◽  
Spin Crossover ◽  
Range Order

Elastic Constants of Binary Liquid Crystalline Mixtures

1998 ◽  
Vol 53 (12) ◽  
pp. 963-976
Author(s):  
A. Kapanowski ◽  
K. Sokalski
Keyword(s):  
Phase Diagram ◽  
Elastic Constants ◽  
Short Range ◽  
Liquid Crystalline ◽  
Particle Distribution ◽  
Distribution Functions ◽  
Binary Liquid ◽  
Small Density ◽  
Nematic Phases ◽  
The One

Abstract Microscopic expressions for the elastic constants of binary liquid crystalline mixtures composed of short rigid uniaxial molecules are derived in the thermodynamic limit at small distorsions and a small density. Uniaxial and biaxial nematic phases are considered. The expressions involve the one-particle distribution functions and the potential energy of two-body short-range interactions. The theory is used to calculate the phase diagram of a mixture of rigid prolate and oblate molecules. The concentration dependence of the order parameters and the elastic constants are obtained. The possibility of phase separation is not investigated.

scholarly journals Molecular dynamics of spin crossover: The (P,T) phase diagram of [Fe(PM-BIA)2(NCS)2]

2013 ◽  
Vol 420 ◽  
pp. 25-34 ◽  
Author(s):  
A. Marbeuf ◽  
S.F. Matar ◽  
P. Négrier ◽  
L. Kabalan ◽  
J.F. Létard ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Phase Diagram ◽  
Spin Crossover ◽  
T Phase
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