Magnetic ordering and ferroelectricity in multiferroic 2HAgFeO2: Comparison between hexagonal and rhombohedral polytypes

Noriki Terada, Dmitry D. Khalyavin, Pascal Manuel, Yoshihiro Tsujimoto, and Alexei A. Belik
Phys. Rev. B 91, 094434 – Published 30 March 2015

Abstract

Magnetic and dielectric properties of the hexagonal triangular lattice antiferromagnet 2HAgFeO2 have been studied by neutron diffraction, magnetic susceptibility, specific heat, pyroelectric current, and dielectric constant measurements. The ferroelectric polarization, P5μC/m2, has been found to appear below 11 K due to a polar nature of the magnetic ground state of the system. In the temperature range of 11 KT18 K, an incommensurate spin density wave (ICM1) with the nonpolar magnetic point group mmm1 and the k1=(0,qb1,0;qb1=0.3900.405) propagation vector takes place. Below 14 K, a proper screw ordering (ICM2) and k2=(0,qb2,0;qb2=0.3850.396) appears as a minor phase which coexists with ICM1 and the ground state down to the lowest measured temperature 5.5 K. No ferroelectric polarization associated with the ICM2 phase was observed in agreement with its nonpolar point group 2221. Finally, a spiral order with cycloid and proper screw components (ICM3), and k3=(qa3,qb3,0;qa3=0.0467,qb3=0.349) emerges below 11 K as the ground state of the system. Based on the deduced magnetic point group 21, we conclude that the ferroelectric polarization in ICM3 is parallel to the c axis and is caused by the inverse Dzyloshinskii-Moriya effect with p1rij×(Si×Sj). Unlike the rhombohedral 3RAgFeO2 polytype, the additional contribution to the macroscopic polarization p2Si×Sj is not allowed in the present case due to the symmetry constraints imposed by the hexagonal lattice of 2HAgFeO2.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
1 More
  • Received 17 February 2015

DOI:https://doi.org/10.1103/PhysRevB.91.094434

©2015 American Physical Society

Authors & Affiliations

Noriki Terada1,*, Dmitry D. Khalyavin2, Pascal Manuel2, Yoshihiro Tsujimoto1, and Alexei A. Belik3,†

  • 1National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan
  • 2ISIS facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, United Kingdom
  • 3International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

  • *TERADA.Noriki@nims.go.jp
  • Alexei.Belik@nims.go.jp

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 91, Iss. 9 — 1 March 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×