Chlorine NMR in CsCoCl3and CsMnCl3and ESR in CsMg(Co)Cl3

摘要

Analysis of the35Cl NMR in single crystals of CsMgCl3, CsMnCl3at 300deg;K and of CsCoCl3at different temperatures yielded the chlorine quadrupole coupling and for the latter two compounds the paramagnetic shift tensors. We found at 300deg;K: for CsMgCl3,ngr;Qthinsp;equals;thinsp;4.465Mcsol;sec,eegr;thinsp;equals;thinsp;0.235; for CsMnCl3,ngr;Qthinsp;equals;thinsp;5.2645Mcsol;sec,eegr;thinsp;equals;thinsp;0.2683(bent bridge),ngr;Qthinsp;equals;thinsp;9.1835Mcsol;sec,eegr;thinsp;equals;thinsp;0.0234(linear bridge); for CsCoCl3,ngr;Qthinsp;equals;thinsp;6.87925Mcsol;sec,eegr;thinsp;equals;thinsp;0.4293. From the ESR spectrum of CsMg(Co)Cl3, thegand hyperfine tensors were determinedlpar;gVerbar;thinsp;equals;thinsp;7.37,gperp;thinsp;equals;thinsp;2.51,AVerbar;lpar;Corpar;thinsp;equals;thinsp;339thinsp;times;thinsp;10minus;4cmminus;1,Aperp;lpar;Corpar;thinsp;equals;thinsp;21thinsp;times;thinsp;10minus;4cmminus;1rpar;. Using these data andDqthinsp;equals;thinsp;660cmminus;1,EPthinsp;equals;thinsp;12 000cmminus;1inferred from the optical spectrum, the spin expectation valueslang;SVerbar;rang;andlang;Sperp;rang;were calculated for CsCoCl3. The following superhyperfine constants parallellpar;AVerbar;rpar;and perpendicularlpar;Aperp;rpar;to the Mesngbnd;Cl bond are computed from the measured paramagnetic shifts:AVerbar;thinsp;equals;thinsp;1.59,Aperp;thinsp;equals;thinsp;1.40(CsMnCl3, ClI, linear bridge),AVerbar;thinsp;equals;thinsp;1.68,Aperp;thinsp;equals;thinsp;1.70(CsMnCl3, ClII, bent bridge),AVerbar;thinsp;equals;thinsp;4.74,Aperp;thinsp;equals;thinsp;1.65(CsCoCl3), all in units 10minus;4cmminus;1. No transition to the ordered magnetic state has been observed for CsMnCl3for temperatures down to 20deg;K, contrary to ESR data in the literature.