String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He

The composite cosmological objects—Kibble-Lazarides-Shafi (KLS) walls bounded by strings and cosmic strings terminated by Nambu monopoles—could be produced during the phase transitions in the early universe. Recent experiments in superfluid ^{3}He reproduced the formation of the KLS domain walls, wh...

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Main Authors: G. E. Volovik, K. Zhang
Format: Article
Language:English
Published: American Physical Society 2020-06-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.2.023263
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author G. E. Volovik
K. Zhang
author_facet G. E. Volovik
K. Zhang
author_sort G. E. Volovik
collection DOAJ
description The composite cosmological objects—Kibble-Lazarides-Shafi (KLS) walls bounded by strings and cosmic strings terminated by Nambu monopoles—could be produced during the phase transitions in the early universe. Recent experiments in superfluid ^{3}He reproduced the formation of the KLS domain walls, which opened the new arena for the detailed study of those objects in a human controlled system with different characteristic lengths. These composite defects are formed by two successive symmetry breaking phase transitions. In the first transition the strings are formed, then in the second transition the string becomes the termination line of the KLS wall. In the same manner, in the first transition monopoles are formed, and then in the second transition these monopoles become the termination points of strings. Here we show that in the vicinity of the second transition the composite defects can be described by relative homotopy groups. This is because there are two well-separated length scales involved, which give rise to two different classes of the degenerate vacuum states, R_{1} and R_{2}, and the composite objects correspond to the nontrivial elements of the group π_{n}(R_{1},R_{2}). We discuss this on example of the so-called polar distorted B phase, which is formed in the two-step phase transition in liquid ^{3}He distorted by aerogel. In this system the string monopoles terminate spin vortices with an even winding number, while KLS string walls terminate on half-quantum vortices. In the presence of magnetic field, vortex skyrmions are formed, and the string monopole transforms to the nexus. We also discuss the integer-valued topological invariants of those objects. Our consideration can be applied to the composite defects in other condensed matter and cosmological systems.
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spelling doaj.art-a75e3a4881624c0fabe49b6eb44810822024-04-12T16:54:51ZengAmerican Physical SocietyPhysical Review Research2643-15642020-06-012202326310.1103/PhysRevResearch.2.023263String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}HeG. E. VolovikK. ZhangThe composite cosmological objects—Kibble-Lazarides-Shafi (KLS) walls bounded by strings and cosmic strings terminated by Nambu monopoles—could be produced during the phase transitions in the early universe. Recent experiments in superfluid ^{3}He reproduced the formation of the KLS domain walls, which opened the new arena for the detailed study of those objects in a human controlled system with different characteristic lengths. These composite defects are formed by two successive symmetry breaking phase transitions. In the first transition the strings are formed, then in the second transition the string becomes the termination line of the KLS wall. In the same manner, in the first transition monopoles are formed, and then in the second transition these monopoles become the termination points of strings. Here we show that in the vicinity of the second transition the composite defects can be described by relative homotopy groups. This is because there are two well-separated length scales involved, which give rise to two different classes of the degenerate vacuum states, R_{1} and R_{2}, and the composite objects correspond to the nontrivial elements of the group π_{n}(R_{1},R_{2}). We discuss this on example of the so-called polar distorted B phase, which is formed in the two-step phase transition in liquid ^{3}He distorted by aerogel. In this system the string monopoles terminate spin vortices with an even winding number, while KLS string walls terminate on half-quantum vortices. In the presence of magnetic field, vortex skyrmions are formed, and the string monopole transforms to the nexus. We also discuss the integer-valued topological invariants of those objects. Our consideration can be applied to the composite defects in other condensed matter and cosmological systems.http://doi.org/10.1103/PhysRevResearch.2.023263
spellingShingle G. E. Volovik
K. Zhang
String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
Physical Review Research
title String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
title_full String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
title_fullStr String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
title_full_unstemmed String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
title_short String monopoles, string walls, vortex skyrmions, and nexus objects in the polar distorted B phase of ^{3}He
title_sort string monopoles string walls vortex skyrmions and nexus objects in the polar distorted b phase of 3 he
url http://doi.org/10.1103/PhysRevResearch.2.023263
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