Etude des propriétés magnétostatiques et des structures magnétiques des chromites des terres rares et d'yttrium

Magnetic Properties of La1−xPrxCrO3

“…In the re"nement, both G W -and G X -type antiferromagnetic spin con"gurations (17) of Cr> were attempted like for the end compound PrCrO (5, 18). These two con"gurations have been reported for the magnetic structure of Cr> in PrCrO (5,18), mainly because of the complexity that the two magnetic peaks are located almost at the same angle (18). This situation was found also in the present data; i.e., the two re#ections of (011) and (110) appear at almost the same angle of 2 &23.53.…”

“…The e!ective paramagnetic moment of Pr> adopted here was 3.62 (10), involving the e!ect from thermally excited states. The deviation below &30 K where no suitable "t has been attained is considered to originate from the combined e!ect of both a crystal "eld around Pr> (21) and a tendency toward magnetic order of Pr> as seen in PrCrO (5,18). The values of M Cr , H I , and obtained here are &40 emu/mol, ca.…”

Hyperfine and crystal field interactions in multiferroic HoCrO3

“…A similar phenomenon was also observed in Ho 2 Ti 2 O 7 , the authors have interpreted it as being due to the fluctuating electronic moments of the Ho [35]. Wan et al, [51] showed both analytically and numerically that indirect magnetic exchange, which is short-range in nature is another driving force for the off-center atomic Fits to the 1.5 K INS data as described in the main text using equation (15). The inelastic peaks at both energy loss and energy gain sides are fitted by convoluting the instrument resolution function determined from vanadium with two delta functions for two inelastic peaks (magenta and green lines) plus one delta function for the elastic peak (blue line).…”

“…On the other hand, earlier reports differ on the aspect of Ho-ordering. Cooperatively induced ordering of Ho in HoCrO 3 was reported at 12 K [15,16] whereas no ordering was observed by Hornreich et.al., down to 1.5 K [17]. Ferroelectricity is observed in RCrO 3 systems only when the R ion is magnetic.…”

“…In HoCrO 3 the exchange coupling between the Cr 3+ nearest neighbors is predominantly antiferromagnetic and they order magnetically below the Néel temperature of T N = 140 K [15]. On the other hand, earlier reports differ on the aspect of Ho-ordering.…”