Magnetic Resonance in the Quasi-2D Square Lattice Easy-Plane Antiferromagnet Ba_2MnGe_2O_7

We report results of a multi-frequency (0.8-60 GHz) electron spin resonance study of the spin dynamics in the quasi-2D square lattice antiferromagnet Ba$_2$MnGe$_2$O$_7$ both in antiferromagnetically ordered and paramagnetic phases. We directly observe two zero-field gaps in the excitation spectrum of the ordered phase, the larger one being due to easy-plane anisotropy, and the smaller one indicates the presence of fourth-order in-plane anisotropy probably related to the multiferroic properties of this compound. We observe effects of hyperfine interaction on the electron spin resonance spectra in the antiferromagnetically ordered state, which turns out to be comparable with in-plane anisotropy. The hyperfine field strength is found from the observed low-temperature electron spin resonance data. The spin dynamics of the paramagnetic phase is characterized by strong broadening of the ESR absorption line, which can be ascribed to the vortex dynamics of a 2D magnet.

[1]  M. Matsuura,et al.  Nontrivial temperature dependence of magnetic anisotropy in multiferroic Ba2MnGe2O7 , 2021, Physical Review Research.

[2]  Y. Onose,et al.  Microwave nonreciprocity of magnon excitations in the noncentrosymmetric antiferromagnet Ba2MnGe2O7 , 2018, Physical Review B.

[3]  G. Roth,et al.  Crystal Structure of Magnetoelectric Ba2MnGe2O7 at Room and Low Temperatures by Neutron Diffraction. , 2018, Inorganic chemistry.

[4]  A. Vasiliev,et al.  Milestones of low-D quantum magnetism , 2018 .

[5]  A. Syromyatnikov,et al.  Breakdown of long-wavelength magnons in cubic antiferromagnets with dipolar forces at small temperature , 2015, 1506.06989.

[6]  B. Schmidt,et al.  Spin fluctuations with two-dimensional XY behavior in a frustrated S=(1)/(2) square-lattice ferromagnet , 2013, 1305.6518.

[7]  A. P. Pyatakov,et al.  Magnetoelectric and multiferroic media , 2012 .

[8]  O. Udalov.  NMR spectrum in a Mn3Al2Ge3O12 noncollinear antiferromagnet , 2011 .

[9]  A. Loidl,et al.  Traces of Z2-Vortices in CuCrO2, AgCrO2, and PdCrO2 , 2011 .

[10]  H. Tsunetsugu,et al.  Magnon pairing in quantum spin nematic , 2010, 1003.4096.

[11]  S. Takamizawa,et al.  Instability of magnons in two-dimensional antiferromagnets at high magnetic fields , 2010, 1002.2470.

[12]  R. Cava,et al.  Vortex dynamics and frustration in two-dimensional triangular chromium lattices , 2009 .

[13]  T. Ono,et al.  Cascade of magnetic-field-induced quantum phase transitions in a spin-1/2 triangular-lattice antiferromagnet. , 2008, Physical review letters.

[14]  D. Mattis.  The Theory of Magnetism Made Simple:An Introduction To Physical Concepts And To Some Useful Mathematical Methods , 2006 .

[15]  R. Cava,et al.  Potential signature of a Kosterlitz-Thouless transition in BaNi2V2O8. , 2003, Physical review letters.

[16]  A. Cuccoli,et al.  Quantum Monte Carlo study ofS=12weakly anisotropic antiferromagnets on the square lattice , 2002, cond-mat/0209316.

[17]  M. Hasenbusch,et al.  Critical behavior of the three-dimensional XY universality class , 2000, cond-mat/0010360.

[18]  U. Toronto,et al.  INSTABILITY OF ANTIFERROMAGNETIC MAGNONS IN STRONG FIELDS , 1998, cond-mat/9808100.

[19]  D. Efremov,et al.  Investigation of the hyperfine interaction in the antiferromagnetic CsMnI3 , 1997 .

[20]  M. Suzuki,et al.  ACCURATE ESTIMATES OF 3D ISING CRITICAL EXPONENTS USING THE COHERENT-ANOMALY METHOD , 1994, cond-mat/9411109.

[21]  V. Safonov,et al.  Nuclear spin wave research , 1991 .

[22]  L. A. Prozorova,et al.  Antiferromagnetic resonance and parametric excitation of spin waves in CsMnCl 3 , 1980 .

[23]  A. Miedema,et al.  Experiments on simple magnetic model systems , 1978 .

[24]  E. A. Turov,et al.  Nuclear magnetic resonance in ferro-and antiferromagnets , 1973 .

[25]  D. Thouless,et al.  Ordering, metastability and phase transitions in two-dimensional systems , 1973 .

[26]  A. Portis,et al.  Nuclear Magnetic Resonance Modes in Magnetic Materials. II. Experiment , 1964 .

[27]  P. Pincus,et al.  Nuclear Magnetic Resonance Modes in Magnetic Material. I. Theory , 1963 .

[28]  A. Heeger,et al.  Double Resonance and Nuclear Cooling in an Antiferromagnet , 1961 .

[29]  W. Hager,et al.  and s , 2019, Shallow Water Hydraulics.

[30]  W. Marsden.  I and J , 2012 .

[31]  S. Cheong,et al.  Multiferroics: a magnetic twist for ferroelectricity. , 2007, Nature materials.

[32]  A. F. Andreev,et al.  REVIEWS OF TOPICAL PROBLEMS: Symmetry and the macroscopic dynamics of magnetic materials , 1980 .

[33]  A. Barouch,et al.  Electron paramagnetic resonance in compounds of transition elements , 1974 .