AUTHOR=Dzero Maxim , Khodas Maxim 

TITLE=Quasiclassical Theory of C4-Symmetric Magnetic Order in Disordered Multiband Metals

JOURNAL=Frontiers in Physics

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2020.00356

DOI=10.3389/fphy.2020.00356

ISSN=2296-424X

ABSTRACT=<p>Recent experimental studies performed in the normal state of iron-based superconductors have discovered the existence of the <italic>C</italic><sub>4</sub>-symmetric (tetragonal) itinerant magnetic state. This state can be described as a spin density wave with two distinct magnetic vectors <inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:math></inline-formula> and <inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math></inline-formula>. Given an itinerant nature of magnetism in iron-pnictides, we develop a quasiclassical theory of tetragonal magnetic order in disordered three-band metal with anisotropic band structure. Within our model we find that the <italic>C</italic><sub>4</sub>-symmetric magnetism competes with the <italic>C</italic><sub>2</sub>-symmetric state with a single <inline-formula><mml:math id="M3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mrow><mml:mi>Q</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:math></inline-formula> magnetic structure vector. Our main results is that disorder promotes tetragonal magnetic state which is in agreement with earlier theoretical studies.</p>