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Title: Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature

Abstract

The zero-temperature angles of magnetic moments in a helix or sinusoidal fan confined to the x y plane, with respect to an in-plane magnetic field H x applied perpendicular to the z axis of a helix or fan, are calculated for commensurate helices and fans with field-independent turn angles k d between moments in adjacent layers of the helix or fan using the classical J 0 - J 1 - J 2 Heisenberg model. For 0 < k d < 4 π / 9 , first-order transitions from helix to a fan structure occur at fields H t as previously inferred, where the fan is found to be approximately sinusoidal. However, for 4 π / 9 ≤ k d ≤ π , different behaviors are found depending on the value of k d and these properties vary nonmonotonically with k d . In this k d range, the change from helix to fanlike structure is usually a crossover with no phase transition between them, although first-order transitions are found for k d = 3 π / 5 and 8 π / 11 and a second-order transition for k d = 3 π / 4 . At a critical field Hmore » c , the fan or fanlike structures exhibit a second-order transition to the paramagnetic state. The H c for a helix undergoing a field-induced change to a fan or fanlike structure is found to be the same as for a sinusoidal fan with the same k d and interlayer interactions. We present analytical expressions for H c versus k d. We also calculated the average x -axis moment per spin μ x ave versus H x for helices and fans with crossovers and phase transitions between them. When smooth helix to fanlike crossovers occur in the range 4 π / 9 ≤ k d ≤ π , μ x ave exhibits an S-shape behavior with increasing H x . The behavior we predict is consistent with μ x ave ( H x ) data previously reported by Sangeetha et al. [Phys. Rev. B 94, 014422 (2016)] for single-crystal EuCo 2 P 2 possessing a helix ground state with k d ≈ 0.85 π . The low-field magnetic susceptibility and the ratio H t / H c are calculated analytically or numerically versus k d for helices, and are shown to approach the respective known limits for k d → 0 .« less

Authors:
 [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics
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:
1394804
Alternate Identifier(s):
OSTI ID: 1378398
Report Number(s):
IS-J-9439
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1702839
Grant/Contract Number:
AC02-07CH11358
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 10; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Johnston, David. Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.96.104405.
Johnston, David. Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature. United States. doi:10.1103/PhysRevB.96.104405.
Johnston, David. Tue . "Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature". United States. doi:10.1103/PhysRevB.96.104405.
@article{osti_1394804,
title = {Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature},
author = {Johnston, David},
abstractNote = {The zero-temperature angles of magnetic moments in a helix or sinusoidal fan confined to the x y plane, with respect to an in-plane magnetic field H x applied perpendicular to the z axis of a helix or fan, are calculated for commensurate helices and fans with field-independent turn angles k d between moments in adjacent layers of the helix or fan using the classical J 0 - J 1 - J 2 Heisenberg model. For 0 < k d < 4 π / 9 , first-order transitions from helix to a fan structure occur at fields H t as previously inferred, where the fan is found to be approximately sinusoidal. However, for 4 π / 9 ≤ k d ≤ π , different behaviors are found depending on the value of k d and these properties vary nonmonotonically with k d . In this k d range, the change from helix to fanlike structure is usually a crossover with no phase transition between them, although first-order transitions are found for k d = 3 π / 5 and 8 π / 11 and a second-order transition for k d = 3 π / 4 . At a critical field H c , the fan or fanlike structures exhibit a second-order transition to the paramagnetic state. The H c for a helix undergoing a field-induced change to a fan or fanlike structure is found to be the same as for a sinusoidal fan with the same k d and interlayer interactions. We present analytical expressions for H c versus k d. We also calculated the average x -axis moment per spin μ x ave versus H x for helices and fans with crossovers and phase transitions between them. When smooth helix to fanlike crossovers occur in the range 4 π / 9 ≤ k d ≤ π , μ x ave exhibits an S-shape behavior with increasing H x . The behavior we predict is consistent with μ x ave ( H x ) data previously reported by Sangeetha et al. [Phys. Rev. B 94, 014422 (2016)] for single-crystal EuCo 2 P 2 possessing a helix ground state with k d ≈ 0.85 π . The low-field magnetic susceptibility and the ratio H t / H c are calculated analytically or numerically versus k d for helices, and are shown to approach the respective known limits for k d → 0 .},
doi = {10.1103/PhysRevB.96.104405},
journal = {Physical Review B},
number = 10,
volume = 96,
place = {United States},
year = {Tue Sep 05 00:00:00 EDT 2017},
month = {Tue Sep 05 00:00:00 EDT 2017}
}

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