Impact of thermal fluctuations on transport in antiferromagnetic semimetals

Youngseok Kim, Moon Jip Park, David G. Cahill, Matthew J. Gilbert

Research output: Contribution to journalArticle

Abstract

Recent demonstrations on manipulating antiferromagnetic (AF) order have triggered a growing interest in antiferromagnetic metal, and potential high-density spintronic applications demand further improvements in the anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are newly discovered materials that possess massless Dirac fermions that are protected by the crystalline symmetries. In this material, a reorientation of the AF order may break the underlying symmetries and induce a finite energy gap. As such, the possible phase transition from the semimetallic to insulating phase gives us a choice for a wide range of resistance, ensuring a large AMR. To further understand the robustness of the phase transition, we study thermal fluctuations of the AF order in AFS at a finite temperature. For macroscopic samples, we find that the thermal fluctuations effectively decrease the magnitude of the AF order by renormalizing the effective Hamiltonian. Our finding suggests that the insulating phase exhibits a gap narrowing at elevated temperatures, which leads to a substantial decrease in AMR. We also examine spatially correlated thermal fluctuations for microscopic samples by solving the microscopic Landau-Lifshitz-Gilbert equation, finding a quantitative difference in the gap narrowing effect from that of the macroscopic sample. For both cases, the semimetallic phase shows a minimal change in its transmission spectrum, illustrating the robustness of the symmetry-protected states in AFS. Our finding may serve as a guideline for estimating and maximizing AMR of the AFS samples at elevated temperatures.

Original languageEnglish (US)
Article number024409
JournalPhysical Review B
Volume98
Issue number2
DOIs
StatePublished - Jul 10 2018

Fingerprint

Enhanced magnetoresistance
Metalloids
metalloids
symmetry
Phase transitions
Hamiltonians
Magnetoelectronics
Fermions
Crystal symmetry
Temperature
retraining
temperature
Energy gap
estimating
Demonstrations
fermions
Metals
Crystalline materials
Hot Temperature
metals

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Impact of thermal fluctuations on transport in antiferromagnetic semimetals. / Kim, Youngseok; Park, Moon Jip; Cahill, David G.; Gilbert, Matthew J.

In: Physical Review B, Vol. 98, No. 2, 024409, 10.07.2018.

Research output: Contribution to journalArticle

@article{fbf48252d32a4e399e155d21b88f196c,
title = "Impact of thermal fluctuations on transport in antiferromagnetic semimetals",
abstract = "Recent demonstrations on manipulating antiferromagnetic (AF) order have triggered a growing interest in antiferromagnetic metal, and potential high-density spintronic applications demand further improvements in the anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are newly discovered materials that possess massless Dirac fermions that are protected by the crystalline symmetries. In this material, a reorientation of the AF order may break the underlying symmetries and induce a finite energy gap. As such, the possible phase transition from the semimetallic to insulating phase gives us a choice for a wide range of resistance, ensuring a large AMR. To further understand the robustness of the phase transition, we study thermal fluctuations of the AF order in AFS at a finite temperature. For macroscopic samples, we find that the thermal fluctuations effectively decrease the magnitude of the AF order by renormalizing the effective Hamiltonian. Our finding suggests that the insulating phase exhibits a gap narrowing at elevated temperatures, which leads to a substantial decrease in AMR. We also examine spatially correlated thermal fluctuations for microscopic samples by solving the microscopic Landau-Lifshitz-Gilbert equation, finding a quantitative difference in the gap narrowing effect from that of the macroscopic sample. For both cases, the semimetallic phase shows a minimal change in its transmission spectrum, illustrating the robustness of the symmetry-protected states in AFS. Our finding may serve as a guideline for estimating and maximizing AMR of the AFS samples at elevated temperatures.",
author = "Youngseok Kim and Park, {Moon Jip} and Cahill, {David G.} and Gilbert, {Matthew J.}",
year = "2018",
month = "7",
day = "10",
doi = "10.1103/PhysRevB.98.024409",
language = "English (US)",
volume = "98",
journal = "Physical Review B",
issn = "2469-9950",
publisher = "American Physical Society",
number = "2",

}

TY - JOUR

T1 - Impact of thermal fluctuations on transport in antiferromagnetic semimetals

AU - Kim, Youngseok

AU - Park, Moon Jip

AU - Cahill, David G.

AU - Gilbert, Matthew J.

PY - 2018/7/10

Y1 - 2018/7/10

N2 - Recent demonstrations on manipulating antiferromagnetic (AF) order have triggered a growing interest in antiferromagnetic metal, and potential high-density spintronic applications demand further improvements in the anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are newly discovered materials that possess massless Dirac fermions that are protected by the crystalline symmetries. In this material, a reorientation of the AF order may break the underlying symmetries and induce a finite energy gap. As such, the possible phase transition from the semimetallic to insulating phase gives us a choice for a wide range of resistance, ensuring a large AMR. To further understand the robustness of the phase transition, we study thermal fluctuations of the AF order in AFS at a finite temperature. For macroscopic samples, we find that the thermal fluctuations effectively decrease the magnitude of the AF order by renormalizing the effective Hamiltonian. Our finding suggests that the insulating phase exhibits a gap narrowing at elevated temperatures, which leads to a substantial decrease in AMR. We also examine spatially correlated thermal fluctuations for microscopic samples by solving the microscopic Landau-Lifshitz-Gilbert equation, finding a quantitative difference in the gap narrowing effect from that of the macroscopic sample. For both cases, the semimetallic phase shows a minimal change in its transmission spectrum, illustrating the robustness of the symmetry-protected states in AFS. Our finding may serve as a guideline for estimating and maximizing AMR of the AFS samples at elevated temperatures.

AB - Recent demonstrations on manipulating antiferromagnetic (AF) order have triggered a growing interest in antiferromagnetic metal, and potential high-density spintronic applications demand further improvements in the anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are newly discovered materials that possess massless Dirac fermions that are protected by the crystalline symmetries. In this material, a reorientation of the AF order may break the underlying symmetries and induce a finite energy gap. As such, the possible phase transition from the semimetallic to insulating phase gives us a choice for a wide range of resistance, ensuring a large AMR. To further understand the robustness of the phase transition, we study thermal fluctuations of the AF order in AFS at a finite temperature. For macroscopic samples, we find that the thermal fluctuations effectively decrease the magnitude of the AF order by renormalizing the effective Hamiltonian. Our finding suggests that the insulating phase exhibits a gap narrowing at elevated temperatures, which leads to a substantial decrease in AMR. We also examine spatially correlated thermal fluctuations for microscopic samples by solving the microscopic Landau-Lifshitz-Gilbert equation, finding a quantitative difference in the gap narrowing effect from that of the macroscopic sample. For both cases, the semimetallic phase shows a minimal change in its transmission spectrum, illustrating the robustness of the symmetry-protected states in AFS. Our finding may serve as a guideline for estimating and maximizing AMR of the AFS samples at elevated temperatures.

UR - http://www.scopus.com/inward/record.url?scp=85049972897&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85049972897&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.98.024409

DO - 10.1103/PhysRevB.98.024409

M3 - Article

AN - SCOPUS:85049972897

VL - 98

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 2

M1 - 024409

ER -