Spin Structure in the bcc Spin-Lattice with Four-Spin Cyclic Exchange Interactions

1980 ◽  
Vol 69 ◽  
pp. 475-485 ◽  
Author(s):  
Kei Yosida
Keyword(s):  
Spin Structure ◽  
Exchange Interactions ◽  
Spin Lattice ◽  
Cyclic Exchange

A 35Cl NQR Study on Exchange Interactions between Paramagnetic [IrCl6]2– Ions

2002 ◽  
Vol 57 (6-7) ◽  
pp. 431-434 ◽  
Author(s):  
Hiroshi Miyoshi ◽  
Keizo Horiuchi ◽  
Ryuichi Ikeda
Keyword(s):  
Relaxation Times ◽  
Exchange Interactions ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
35Cl Nqr ◽  
Temperature Dependences ◽  
Field Fluctuations ◽  
Paramagnetic Ions ◽  
Exchange Parameters

The 35Cl and 37Cl NQR frequencies and spin-lattice relaxation times T1Q in paramagnetic M2IrCl6 (M = NH4, Cs) were measured at 4 - 350 K. The observed temperature dependences were attributed to EFG fluctuations caused by lattice vibrations and magnetic field fluctuations caused by paramagnetic ions. The exchange parameters in the NH4 and Cs salts were calculated from 35Cl NQR T1Q to be 8.6 K and 1.8 K respectively. 37Cl data yielded 9.1 K and 2.1 K respectively. The obtained lattice constant dependence of J values was explained by considering Ir-Cl Cl-Ir superexchange interaction

scholarly journals Magnetic ordering and fluctuation in Kagome lattice anti-ferromagnets, Fe and Cr jarosites

2001 ◽  
Vol 79 (11-12) ◽  
pp. 1511-1516 ◽  
Author(s):  
M Nishiyama ◽  
T Morimoto ◽  
S Maegawa ◽  
T Inami ◽  
Y Oka
Keyword(s):  
Magnetic Transition ◽  
Magnetic Ordering ◽  
Exchange Interactions ◽  
Lattice Relaxation ◽  
Spin Correlation ◽  
Spin Lattice Relaxation ◽  
Kagome Lattice ◽  
Kagomé Lattice ◽  
Spin Lattice ◽  
High Temperature Expansion

Jarosite family compounds, KFe3(OH)6(SO4)2 (abbreviated to Fe jarosite) and KCr3(OH)6(SO4)2 (Cr jarosite) are typical examples of Heisenberg anti-ferromagnets on the Kagome lattice and have been investigated by means of magnetization and NMR experiments. The susceptibility of Cr jarosite deviates from the Curie–Weiss law due to the short-range spin correlation below about 150 K and shows the magnetic transition at 4.2 K, while Fe jarosite has the transition at 65 K. The measured susceptibility fits well with the calculated one on the high-temperature expansion for the Heisenberg anti-ferromagnet on the Kagome lattice. The values of the exchange interactions of Cr jarosite and Fe jarosite are derived to be JCr = 4.9 K and JFe = 23 K, respectively. The 1H-NMR spectra of Fe jarosite suggest that the ordered spin structure is the q = 0 type 120° configuration with +1 chirality. The transition is considered to be caused by a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T1, of Fe jarosite in the ordered phase decreases sharply with decreasing temperature and can be well explained by the two-magnon process of spin wave with the anisotropy. PACS No.: 75.25+z

scholarly journals Pressure-induced normal-incommensurate-commensurate phase transitions in TiPO4

2014 ◽  
Vol 70 (a1) ◽  
pp. C263-C263 ◽  
Author(s):  
Maxim Bykov ◽  
Elena Bykova ◽  
Leonid Dubrovinsky ◽  
Michael Hanfland ◽  
Hanns-Peter Liermann ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Degrees Of Freedom ◽  
Spin Exchange ◽  
Exchange Interactions ◽  
Quantum Spin ◽  
Singlet Ground State ◽  
Transition Temperatures ◽  
Spin Lattice ◽  
Commensurate Phase

The complex interplay between spin, charge, orbital, and lattice degrees of freedom has made low-dimensional quantum spin magnets with strong antiferromagnetic (AF) spin-exchange coupling prime candidates for studying unusual magnetic phenomena. A progressive spin-lattice dimerization in one-dimensional AF Heisenberg chains, which occurs below a critical temperature and induces a singlet ground state with a magnetic gap, is commonly referred to as spin-Peierls (SP) transition. Recently, the compounds TiOX (X = Cl, Br) and TiPO4have been intensively investigated due to their unconventional behavior [1,2]. Unlike standard SP systems, TiOX and TiPO4undergo a sequence of normal-incommensurate-commensurate phase transitions on cooling at remarkably high transition temperatures. The transition temperatures are related to the direct exchange interactions between Ti ions, which increases strongly with decreasing the distance between the Ti ions, and therefore is very sensitive to the applied hydrostatic pressure. We have performed pressure-dependent single-crystal X-ray diffraction of TiPO4using synchrotron radiation. TiPO4undergoes a pressure-induced pahse transiton towards an incommensurate phase already below 10 GPa. This transformation is followed by the lock-in phase transition to the dimerized SP phase. Both structures are analogous to those at low temperatures, but reveal significantly larger modulation amplitudes. In this contribution we will present the detailed discussion of the high-pressure structures of TiPO4and their behavior on compression. Furthermore, similarities and differences of high-pressure phase diagrams of TiOCl and TiPO4and discrepancies between predicted and observed structures will be considered.

Sign in / Sign up

Export Citation Format

Share Document