Theory of the helical spin crystal: a candidate for the partially ordered state of MnSi

Abstract

MnSi is an itinerant magnet which at low temperatures develops a helical spin density wave. Under pressure it undergoes a transition into an unusual partially ordered state whose nature is debated. Here we propose that the helical spin crystal (the magnetic analog of a solid) is a useful starting point to understand partial order in MnSi. We consider different helical spin crystals and determine conditions under which they may be energetically favored. The most promising candidate has bcc structure and is reminiscent of the blue phase of liquid-crystals in that it has line-nodes of magnetization protected by symmetry. We introduce a Landau theory to study the properties of these states, in particular the effect of crystal anisotropy, magnetic field and disorder. These results compare favorably with existing data on MnSi from neutron scattering and magnetic field studies. Future experiments to test this scenario are also proposed.

4 pages, 2 figures, minor text changes

Cited by in corpus (16)

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• Fermi-liquid instabilities at magnetic quantum phase transitions
• Skyrmions and Anomalous Hall Effect in a Dzyloshinskii-Moriya Spiral Magnet
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• Fermi liquid instabilities in the spin channel
• Theory of helical spin crystals: phases, textures and properties
• Chirality induced anomalous-Hall effect in helical spin crystals
• Crystalline phases in chiral ferromagnets: Destabilization of helical order
• 0-pi Transitions in a Superconductor/Chiral Ferromagnet/Superconductor Junction induced by a Homogeneous Cycloidal Spiral
• Ultrasonic studies of the magnetic phase transition in MnSi
• Peculiar behavior of the electrical resistivity of MnSi at the ferromagnetic phase transition
• Origin and consequence of an unpinned helical magnet: application to partial order in MnSi under pressure
• A microscopic model for spiral ordering along (110) on the MnSi lattice
• Small-angle interband scattering as the origin of the $T^{3/2}$ resistivity in MnSi
• Theoretical proposal predicting anomalous magnetoresistance and quadratic Hall effect in the partially ordered state of MnSi
• Supplementary Information for: 'Spontaneous Skyrmion Ground States in Magnetic Metals'