@article{f343e97f6b964da292b95f5c5824d62c,
title = "Degenerate ground state in the classical pyrochlore antiferromagnet Na3Mn(CO3)2Cl",
abstract = "In an ideal classical pyrochlore antiferromagnet without perturbations, an infinite degeneracy in a ground state leads to the absence of magnetic order and a spin-glass transition. Here we present Na3Mn(CO3)2Cl as a new candidate compound where classical spins are coupled antiferromagnetically on the pyrochlore lattice and report its structural and magnetic properties. The temperature dependences of the magnetic susceptibility and heat capacity and the magnetization curve are consistent with those of an S=5/2 pyrochlore lattice antiferromagnet with nearest-neighbor interactions of 2 K. Neither an apparent signature of a spin-glass transition nor magnetic order is detected in magnetization and heat capacity measurements or powder neutron diffraction experiments. On the other hand, antiferromagnetic short-range order of the nearest neighbors is evidenced by the Q dependence of the diffuse scattering which develops around 0.85{\AA}-1. A high degeneracy near the ground state in Na3Mn(CO3)2Cl is supported by the magnetic entropy, estimated as almost 4JK-2mol-1 at 0.5 K.",
author = "Kazuhiro Nawa and Daisuke Okuyama and Maxim Avdeev and Hiroyuki Nojiri and Masahiro Yoshida and Daichi Ueta and Hideki Yoshizawa and Sato, {Taku J.}",
note = "Funding Information: We thank H. Sagayama for support with the single-crystal x-ray diffraction experiment, S. Asai and T. Masuda for help with heat capacity measurements, and T. Hiraiwa and K. Yamauchi for fruitful discussions. This work was partly supported by a Grant-In-Aid for Scientific Research (Grant No. 17K18744) from MEXT of Japan, the CORE Laboratory Research Program ”Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” of the Network Joint Research Center for Materials and Devices, and the Motizuki Fund of Yukawa Memorial Foundation. High-field magnetization and heat capacity measurements were carried out under the Inter-University Cooperative Research Program of the Institute for Materials Research, Tohoku University, and the Visiting Researcher's Program of the Institute for Solid State Physics, University of Tokyo, respectively. Synchrotron x-ray diffraction experiments were performed with the approval of the Photon Factory Program Advisory Committee (No. 2016G143). Travel expenses for the experiment on ECHIDNA at ANSTO were partly sponsored by the General User Program of ISSP-NSL, University of Tokyo. Publisher Copyright: {\textcopyright} 2018 American Physical Society.",
year = "2018",
month = oct,
day = "18",
doi = "10.1103/PhysRevB.98.144426",
language = "English",
volume = "98",
journal = "Physical Review B",
issn = "2469-9950",
publisher = "American Physical Society",
number = "14",
}