Abstract
The geometrically frustrated two-dimensional triangular lattice magnets A4B′B2O12 (A=Ba, Sr, La; B′=Co, Ni, Mn; B=W, Re) have been studied by x-ray diffraction, ac and dc susceptibilities, powder neutron diffraction, and specific-heat measurements. The results reveal the following: (i) The samples containing Co2+ (effective spin-1/2) and Ni2+ (spin-1) ions with small spin numbers exhibit ferromagnetic (FM) behavior and ordering, respectively, while the sample containing Mn2+ (spin-5/2) ions with a large spin number exhibits antiferromagnetic (AFM) ordering. We ascribe these spin-number-manipulated ground states to the competition between the AFM B′-O-O-B′ and FM B′-O-B-O-B′ superexchange interactions. (ii) The chemical pressure introduced into the Co-containing samples through the replacement of different-size ions on the A site finely tunes the FM behavior temperature of the system. This effect is not simply governed by the lattice parameters and requires more precise structural measurements to elucidate.
| Original language | English |
|---|---|
| Article number | 174438 |
| Journal | Physical Review B |
| Volume | 95 |
| Issue number | 17 |
| DOIs | |
| State | Published - May 25 2017 |
Funding
R.R. and H.D.Z. are grateful for the support from NSF DMR through Grant No. DMR-1350002. J.M. is grateful for the support of the Ministry of Science and Technology of China (Grant No. 2016YFA0300500). The research at HFIR/ORNL was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, and U.S. Department of Energy. The work at NHMFL is supported by NSF Grant No. DMR-1157490 and the state of Florida.