Multiferroic quantum material Ba2Cu1−xMnxGe2O7 (0 ≤ x ≤ 1) as a potential candidate for frustrated Heisenberg antiferromagnet

npj Quantum Materials, vol. 9

Abstract

Abstract Multiferroic Ba2CuGe2O7 was anticipated as a potential member of the exciting group of materials hosting a skyrmion or vortex lattice because of its profound Dzyaloshinskii–Moriya interaction (DMI) and the absence of single ion anisotropy (SIA). This phase, however, could not be evidenced and instead, it exhibits a complex incommensurate antiferromagnetic (AFM) cycloidal structure. Its sister compound Ba2MnGe2O7, in contrast, is characterized by a relatively strong in-plane exchange interaction that competes with a non-vanishing SIA and the weak DMI, resulting in a quasi-two-dimensional commensurate AFM structure. Considering this versatility in the magnetic interactions, a mixed solid solution of Cu and Mn in Ba2Cu1−xMnxGe2O7 can hold an interesting playground for its interactive DMI and SIA depending on the mixed spin states of the transition metal ions towards the skyrmion physics. Here, we present a detailed study of the micro- and macroscopic spin structure of the Ba2Cu1−xMnxGe2O7 solid solution series using high-resolution neutron powder diffraction techniques. We have developed a remarkably rich magnetic phase diagram as a function of the applied magnetic field and x, which consists of two end-line phases separated by a potentially quantum-critical phase at x = 0.57. An AFM conical structure at zero magnetic field is demonstrated to persist up to x = 0.50. Our results provide crucial information on the spin structure and magnetic properties, which are necessary for the general understanding and theoretical developments on multiferroicity in the frame of skyrmion type or frustrated AFM lattice where DMI and SIA play an important role.

Authors 11

1. Henrik Thoma corresponding Aachen Institut für Kristallographie

   Heinz Maier-Leibnitz Zentrum · RWTH Aachen University

   Affiliation as printed

   Institut für Kristallographie, RWTH Aachen Universität, Aachen, Germany

   Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany

2. Rajesh Dutta corresponding Aachen Institut für Kristallographie

   Heinz Maier-Leibnitz Zentrum · RWTH Aachen University

   Affiliation as printed

   Institut für Kristallographie, RWTH Aachen Universität, Aachen, Germany

   Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany

3. Vladimir M. Hutanu corresponding Aachen Institut für Kristallographie

   Heinz Maier-Leibnitz Zentrum · RWTH Aachen University

   Affiliation as printed

   Institut für Kristallographie, RWTH Aachen Universität, Aachen, Germany

   Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany

4. V. Granata

   University of Salerno

   Affiliation as printed

   Department of Physics “E.R. Caianiello”, University of Salerno, Fisciano, Italy

   Department of Physics "E.R. Caianiello", University of Salerno, Fisciano, Italy

5. R. Fittipaldi

   University of Salerno

   Affiliation as printed

   CNR-SPIN c/o University of Salerno, Fisciano, Italy

6. Qiang Zhang

   Oak Ridge National Laboratory

   Affiliation as printed

   Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

7. Jeffrey W. Lynn

   National Institute of Standards and Technology · NIST Center for Neutron Research

   Affiliation as printed

   NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA

8. P. Čermák

   Charles University

   Affiliation as printed

   Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

9. N. Khan

   University of Augsburg

   Affiliation as printed

   Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, Augsburg, Germany

10. S. Nandi

    Forschungszentrum Jülich · Jülich Aachen Research Alliance

    Affiliation as printed

    Jülich Centre for Neutron Science (JCNS) and Peter Grünberg Institut (PGI), JARA-FIT, Forschungszentrum Jülich, Jülich, Germany

11. Manuel Angst

    Forschungszentrum Jülich · Jülich Aachen Research Alliance

    Affiliation as printed

    Jülich Centre for Neutron Science (JCNS) and Peter Grünberg Institut (PGI), JARA-FIT, Forschungszentrum Jülich, Jülich, Germany