Observation of Majorana Quasiparticles’ Edge States in Superfluid 3He

Abstract

We suggest in this article the nuclear magnetic resonance (NMR) method of observation and investigations of Majorana fermions at the edge of Topological Insulator, superfluid 3 He-B. The Majorana fermions form the remarkable quantum state of condensed matter where particle-like and antiparticle (holelike) excitations are indistinguishable. They have been observed recently by deviation of the temperature dependence of the superfluid 3 He-B heat capacity from the well-known exponential law for Bogoliubov quasiparticles at the world limit of ultra-low temperatures. The experimental data are well described by adding the heat capacity of Majorana quasiparticles' edge states with zero energy gap. We report here the results of the similar experiments with extended temperature range down to 125 lK. The possible way to detect these states by means of NMR is also discussed.

Symmetry-Protected Topological Superfluids and Superconductors —From the Basics to3He—

“…Recent transverse acoustic impedance measurements with an well-controlled surface condition succeeded in the spectroscopy of surface bound states, which captured the surface density of states peculiar to the Majorana cone. 58) The characteristics of the Majorana cone were also observed in the heat capacity measurement by Bunkov et al 53,54) In addition, SQUID-NMR experiments reported the observation of the' z domain wall. 44) These experimental observations are the first step to further capturing a hallmark of chiral and helical Majorana fermions.…”

“…[52][53][54] In Ref. 52, they reported the clear deviation of CðTÞ from that of the bulk 3 He-B in the vicinity of T c , which is attributed to the sufficient zero-energy density of states at the diffusive surface.…”

“…The local density of states gives rise to a power-law behavior of the specific heat, CðTÞ / T 2 , for low temperatures T ( T c . 255) The measurement of CðTÞ at lower T down to T ¼ 135 µK was performed by Bunkov et al 53,54) They observed a 10% deviation from the heat capacity of the bulk superfluid 3 He-B at T ¼ 135 µK. The deviation is attributed to the contribution from the surface Majorana cone.…”

“…50,51) (iv) The surface density of states peculiar to gapless quasiparticle states has already been observed in specific heat measurements and high-precision spectroscopy based on transverse acoustics under well-controlled surface conditions. [52][53][54][55][56][57][58] Motivated by puzzling issues on the intrinsic angular momentum paradox, investigations on the nontrivial momentum space topology were first initiated in 3 He by Stone et al 59,60) and Volovik,61,62) independently. In connection with an analogue of a two-dimensional 3 He-A thin film to the quantum Hall effect and gauge theories, Volovik 61,[63][64][65] further uncovered the remarkable fact that the pairwise point nodes on the Fermi surface are protected by the first Chern number as a "magnetic" monopole, and low-energy quasiparticles near the Fermi points behave as chiral Weyl fermions.…”

Enhancement of the Spin Pumping Effect by Magnon Confluence Process in YIG/Pt Bilayers

“…Among them one can note classical magnon dynamics effects like parametrically stimulated recovery of a microwave signal, [1,2] magnon wavefront reversal, [3,4] magnetic solitons [5,6] and two-dimensional spin-wave bullets, [7,8] strain-induced magnon effects, [9] nonreciprocity and transformation of spin waves in ferromagnetic-semiconductor and ferromagnetic-multiferroic structures, [10,11] and many others. Simultaneously, novel quantum macroscopic collective phenomena, such as Bose-Einstein condensation (BEC) of magnons, [12][13][14][15] magnon vortices [16] and supercurrents, [17][18][19] as well as a space-time crystal in the magnon BEC [20] open new directions for the utilization of the magnon system. The large variety of the effects in magnon systems is observed due to the manifold of multi-magnon scattering processes in combination with the inherent nonlinearity in a magnetic medium.…”