Evolution of magnetic properties in the normal spinel solid solution Mg 1xCu xCr 2O 4

Moureen C. Kemei, Stephanie L. Moffitt, Daniel P. Shoemaker, Ram Seshadri

Research output: Contribution to journalArticlepeer-review

Abstract

We examine the evolution of magnetic properties in the normal spinel oxides Mg 1xCu xCr 2O 4 using magnetization and heat capacity measurements. The end-member compounds of the solid solution series have been studied in some detail because of their very interesting magnetic behavior. MgCr 2O 4 is a highly frustrated system that undergoes a first-order structural transition at its antiferromagnetic ordering temperature. CuCr 2O 4 is tetragonal at room temperature as a result of JahnTeller active tetrahedral Cu 2+ and undergoes a magnetic transition at 135K. Substitution of magnetic cations for diamagnetic Mg 2+ on the tetrahedral A site in the compositional series Mg 1xCu xCr 2O 4 dramatically affects magnetic behavior. In the composition range 0x0.3, the compounds are antiferromagnetic. A sharp peak observed at 12.5K in the heat capacity of MgCr 2O 4 corresponding to a magnetically driven first-order structural transition is suppressed even for small x. Uncompensated magnetismwith open magnetization loopsdevelops for samples in the x range 0.43x1. Multiple magnetic ordering temperatures and large coercive fields emerge in the intermediate composition range 0.43x0.47. The Néel temperature increases with increasing x across the series while the value of the CurieWeiss CW decreases. A magnetic temperaturecomposition phase diagram of the solid solution series is presented.

Original languageEnglish (US)
Article number046003
JournalJournal of Physics Condensed Matter
Volume24
Issue number4
DOIs
StatePublished - Feb 1 2012
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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