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Lecture A.A. Nugroho


29 May 2009 FWN-Building 5118.-156, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. A.A. Nugroho
Affiliation: Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Indonesia
Title: μ -SR study of multiferroic CoCr2O4
Date: Fri May 29, 2009
Start: 15.00
Location: FWN-Building 5118.-156
Host: P.H.M. van Loosdrecht/T.T.M. Palstra
Telephone: +31 50 363 4440


The spinel compound CoCr2O4 has been shown to undergo successive magnetic transitions associated with the occurrence of ferrimagnetic phase, the low-temperature magnetic phase of transverse conical spin structure, and the lowest-temperature phase of short-range magnetic order, respectively. Those different temperature regimes of distinct magnetic order can be probed by  m-SR measurement in zero external field. The measured asymmetry data were fitted by two component and Kubo-Toyabe model representing the general of both slow and fast decay components of the relaxation fluctuations. The result shows abrupt changes of the decay rates at temperature around the well-known transition temperatures determined by magnetization measurement and reveals that the relative changes in the magnetic order of the sample. The measurement performed in the presence of external longitudinal fields (LF) at low temperature was found to exhibit gradual recovery of the asymmetry with increasing field along the decreasing delay rate, although the recovery was incomplete even at 4kG LF, implying the strength of internal field fluctuations. The correlation between those findings and the multiferroic properties of the conical ferrimagnetic will be presented.

Last modified:22 October 2012 2.31 p.m.