### Abstract

We theoretically address the problem of cubic B20 helimagnets with a small concentration câ‰1 of defect bonds in external magnetic field H, which is relevant to mixed B20 compounds at small dopant concentrations. We assume that the Dzyaloshinskii-Moriya interaction and the exchange coupling constant are changed on imperfect bonds which leads to distortion of the conical spiral ordering. In a one-impurity problem we find that the distortion of the spiral pitch is long ranged and it is governed by the Poisson equation for an electric dipole. The variation of the cone angle is described by the screened Poisson equation for two electric charges with the screening length being of the order of the spiral period. We calculate corrections to the spiral vector and to the cone angle at finite c. The correction to the spiral vector is shown to be independent of H. We demonstrate that diffuse neutron scattering caused by disorder appears in the elastic cross section as power-law decaying tails centered at magnetic Bragg peaks.

Original language | English |
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Article number | 134412 |

Number of pages | 8 |

Journal | Physical Review B-Condensed Matter |

Volume | 99 |

Issue number | 13 |

DOIs | |

Publication status | Published - 8 Apr 2019 |

### Scopus subject areas

- Physics and Astronomy(all)

### Cite this

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**Cubic B20 helimagnets with quenched disorder in magnetic field.** / Utesov, O.; Syromyatnikov, A.

Research output

TY - JOUR

T1 - Cubic B20 helimagnets with quenched disorder in magnetic field

AU - Utesov, O.

AU - Syromyatnikov, A.

PY - 2019/4/8

Y1 - 2019/4/8

N2 - We theoretically address the problem of cubic B20 helimagnets with a small concentration câ‰1 of defect bonds in external magnetic field H, which is relevant to mixed B20 compounds at small dopant concentrations. We assume that the Dzyaloshinskii-Moriya interaction and the exchange coupling constant are changed on imperfect bonds which leads to distortion of the conical spiral ordering. In a one-impurity problem we find that the distortion of the spiral pitch is long ranged and it is governed by the Poisson equation for an electric dipole. The variation of the cone angle is described by the screened Poisson equation for two electric charges with the screening length being of the order of the spiral period. We calculate corrections to the spiral vector and to the cone angle at finite c. The correction to the spiral vector is shown to be independent of H. We demonstrate that diffuse neutron scattering caused by disorder appears in the elastic cross section as power-law decaying tails centered at magnetic Bragg peaks.

AB - We theoretically address the problem of cubic B20 helimagnets with a small concentration câ‰1 of defect bonds in external magnetic field H, which is relevant to mixed B20 compounds at small dopant concentrations. We assume that the Dzyaloshinskii-Moriya interaction and the exchange coupling constant are changed on imperfect bonds which leads to distortion of the conical spiral ordering. In a one-impurity problem we find that the distortion of the spiral pitch is long ranged and it is governed by the Poisson equation for an electric dipole. The variation of the cone angle is described by the screened Poisson equation for two electric charges with the screening length being of the order of the spiral period. We calculate corrections to the spiral vector and to the cone angle at finite c. The correction to the spiral vector is shown to be independent of H. We demonstrate that diffuse neutron scattering caused by disorder appears in the elastic cross section as power-law decaying tails centered at magnetic Bragg peaks.

KW - MNSI

UR - http://www.scopus.com/inward/record.url?scp=85064107003&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.99.134412

DO - 10.1103/PhysRevB.99.134412

M3 - статья

VL - 99

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 13

M1 - 134412

ER -