Strongly reduced band gap in NiMn2O4 due to cation exchange

Jhih Rong Huang, Han Hsu, Ching Cheng

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


NiMn2O4 is extensively used as a basis material for temperature sensors due to its negative temperature coefficient of resistance (NTCR), which is commonly attributed to the hopping mechanism involving coexisting octahedral-site Mn4+ and Mn3+. Using density-functional theory + Hubbard U calculations, we identify a ferrimagnetic inverse spinel phase as the collinear ground state of NiMn2O 4. By a 12.5% cation exchange, a mixed phase with slightly higher energy can be constructed, accompanied by the formation of an impurity-like band in the original 1 eV band gap. This impurity-like band reduces the gap to 0.35 eV, suggesting a possible source of NTCR.

Original languageEnglish
Pages (from-to)149-152
Number of pages4
JournalJournal of Magnetism and Magnetic Materials
StatePublished - May 2014


  • Density functional calculation
  • Nickel manganite


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