Robust and Clean Majorana Zero Mode in the Vortex Core of High-Temperature Superconductor (Li0.84Fe0.16)OHFeSe

Abstract

The Majorana fermion, which is its own anti-particle and obeys non-abelian statistics, plays a critical role in topological quantum computing. It can be realized as a bound state at zero energy, called a Majorana zero mode (MZM), in the vortex core of a topological superconductor, or at the ends of a nanowire when both superconductivity and strong spin orbital coupling are present. A MZM can be detected as a zero-bias conductance peak (ZBCP) in tunneling spectroscopy. However, in practice, clean and robust MZMs have not been realized in the vortices of a superconductor, due to contamination from impurity states or other closely-packed Caroli-de Gennes-Matricon (CdGM) states, which hampers further manipulations of MZMs. Here using scanning tunneling spectroscopy, we show that a ZBCP well separated from the other discrete CdGM states exists ubiquitously in the cores of free vortices in the defect free regions of (Li0.84Fe0.16)OHFeSe, which has a superconducting transition temperature of 42 K. Moreover, a Dirac-cone-type surface state is observed by angle-resolved photoemission spectroscopy, and its topological nature is confirmed by band calculations. The observed ZBCP can be naturally attributed to a MZM arising from this chiral topological surface states of a bulk superconductor. (Li0.84Fe0.16)OHFeSe thus provides an ideal platform for studying MZMs and topological quantum computing. 2

Quasiparticle interference and symmetry of superconducting order parameter in strongly electron-doped iron-based superconductors

“…In any case, the situation is somewhat more complicated than anticipated in [28], since the effect of spin-orbit interaction on pairing needs to be taken into account as well. Moreover, recent observation of Majorana zero modes in (Li 0.84 Fe 0.16 )OHFeSe [29] suggests possible broader implications of the SOC for the Cooper-pairing in electron doped intercalated iron-based superconductors. Note that in contrast to [28], no Zn substitution was used in [29].…”

“…Moreover, recent observation of Majorana zero modes in (Li 0.84 Fe 0.16 )OHFeSe [29] suggests possible broader implications of the SOC for the Cooper-pairing in electron doped intercalated iron-based superconductors. Note that in contrast to [28], no Zn substitution was used in [29]. The amount of Zn, however, is relatively small (less than 2%).…”

Majorana corner and hinge modes in second-order topological insulator/superconductor heterostructures

“…In a later influential paper[30], Qi et al pointed out that quantum anomalous Hall insulator (QAHI)/SC heterostructures provide a simple realization of 2d chiral TSCs which harbor not only vortex-core MZMs, but also chiral Majorana edge modes. These two theoretical works have triggered a lot of experimental works on TI(QAHI)/SC heterostructures [28,29,[31][32][33][34][35][36][37][38][39][40][41], and remarkable progress in detecting vortex-core MZMs has been witnessed in recent years [28,29,40,41].Very recently, TIs and TSCs have been generalized to include their higher-order counterparts [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]. Importantly, higher-order TIs (HOTIs) and TSCs (HOTSCs) have extended the conventional bulk-boundary correspondence.…”

“…In a later influential paper [30], Qi et al pointed out that quantum anomalous Hall insulator (QAHI)/SC heterostructures provide a simple realization of 2d chiral TSCs which harbor not only vortex-core MZMs, but also chiral Majorana edge modes. These two theoretical works have triggered a lot of experimental works on TI(QAHI)/SC heterostructures [28,29,[31][32][33][34][35][36][37][38][39][40][41], and remarkable progress in detecting vortex-core MZMs has been witnessed in recent years [28,29,40,41].…”

Revealing the nonlocal coherent nature of Majorana devices from dissipative teleportation

“…non-Abelian braiding statistics [3][4][5][6], and has potential applications in quantum information processing and topological quantum computation [6,7]. Many proposals for realizing MZMs in topological superconductors (SCs) have been put forward [8][9][10][11][12][13][14][15], and lead to recent experimental progress in the realization and detection of MZM in both one-dimensional [16][17][18][19][20][21][22][23][24][25][26][27] and two-dimensional platforms [28][29][30][31][32][33][34]. The quantized Majorana conductance at 2e 2 /h, observed in nanowire devices [27], closes one chapter in tunneling spectroscopy based on the simplest device set-ups.…”