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Title: EuCo 2P 2: A Model Molecular-Field Helical Heisenberg Antiferromagnet

Abstract

The metallic compound EuCo 2P 2 with the body-centered tetragonal ThCr 2Si 2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below T N=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo 2P 2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ, high-field magnetization, and magnetic heat capacity of EuCo 2P 2 single crystals at temperature T≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~T 3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo 2P 2 and the related compound BaCo 2P 2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo 2Pmore » 2 and BaCo 2P 2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. Additionally, the calculations also find ferromagnetic Eu–Eu exchange interactions within the ab plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χ ab(T≤TN).« less

Authors:
 [1];  [2];  [1];  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  2. Swiss Federal Lab. for Materials Science and Technology (Empa), Dubendorf (Switzerland); Federal Inst. of Technology, Zurich (Switzerland)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1311820
Alternate Identifier(s):
OSTI ID: 1264795
Report Number(s):
IS-J-8865
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 1; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Sangeetha, N. S., Cuervo-Reyes, Eduardo, Pandey, Abhishek, and Johnston, D. C. EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet. United States: N. p., 2016. Web. doi:10.1103/PhysRevB.94.014422.
Sangeetha, N. S., Cuervo-Reyes, Eduardo, Pandey, Abhishek, & Johnston, D. C. EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet. United States. doi:10.1103/PhysRevB.94.014422.
Sangeetha, N. S., Cuervo-Reyes, Eduardo, Pandey, Abhishek, and Johnston, D. C. Tue . "EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet". United States. doi:10.1103/PhysRevB.94.014422. https://www.osti.gov/servlets/purl/1311820.
@article{osti_1311820,
title = {EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet},
author = {Sangeetha, N. S. and Cuervo-Reyes, Eduardo and Pandey, Abhishek and Johnston, D. C.},
abstractNote = {The metallic compound EuCo2P2 with the body-centered tetragonal ThCr2Si2 structure containing Eu spins-7/2 was previously shown from single-crystal neutron diffraction measurements to exhibit a helical antiferromagnetic (AFM) structure below TN=66.5 K with the helix axis along the c axis and with the ordered moments aligned within the ab plane. Here we report crystallography, electrical resistivity, heat capacity, magnetization, and magnetic susceptibility measurements on single crystals of this compound. We demonstrate that EuCo2P2 is a model molecular-field helical Heisenberg antiferromagnet from comparisons of the anisotropic magnetic susceptibility χ, high-field magnetization, and magnetic heat capacity of EuCo2P2 single crystals at temperature T≤TN with the predictions of our recent formulation of molecular-field theory. Values of the Heisenberg exchange interactions between the Eu spins are derived from the data. The low-T magnetic heat capacity ~T3 arising from spin-wave excitations with no anisotropy gap is calculated and found to be comparable to the lattice heat capacity. The density of states at the Fermi energy of EuCo2P2 and the related compound BaCo2P2 are found from the heat capacity data to be large, 10 and 16 states/eV per formula unit for EuCo2P2 and BaCo2P2, respectively. These values are enhanced by a factor of ~2.5 above those found from DFT electronic structure calculations for the two compounds. Additionally, the calculations also find ferromagnetic Eu–Eu exchange interactions within the ab plane and AFM interactions between Eu spins in nearest- and next-nearest planes, in agreement with the MFT analysis of χab(T≤TN).},
doi = {10.1103/PhysRevB.94.014422},
journal = {Physical Review B},
number = 1,
volume = 94,
place = {United States},
year = {2016},
month = {7}
}

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