Tuning topological surface magnetism by bulk alloying

Abstract

Deploying an analytical atomistic model of the bulk band structure of the IV-VI semiconductors we connect the spin structure of the topological surface state to the crystal field and spin orbit coupling parameters of the bulk material. While the Dirac-Weyl (or equivalently, Rashba) type topological surface state is often assumed universal, we show that the physics of the surface state is strikingly non-universal. To see this explicitly we calculate the RKKY interaction, which may be viewed as a probe of this surface state spin structure, finding its qualitative form depends on the values the bulk spin-orbit and crystal field parameters take. This opens the way to tune the spin interaction on the surface of a IV-VI topological insulator by, for instance varying the composition of the IV-VI ternary compounds, as well as highlighting the importance of the connection between bulk and surface physics in topological insulators. arXiv:1711.10760v1 [cond-mat.mes-hall]

RKKY interaction on the surface of three-dimensional Dirac semimetals

“…At low chemical potentials, such that |µx|/v < 1, the RKKY interaction has a negative sign, and thus favors a ferromagnetic alignment of spins. This result is reminiscent of the interaction between two magnetic impurities on the surface of a topological insulator [8][9][10][11][12][13][14][15].…”

“…Since the mid-twentieth century it has been understood that localized spins in metals can interact by means of the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism [1][2][3]. This indirect exchange coupling is mediated by the conduction electrons and has been investigated in materials of different nature such as disordered metals [4], superconductors [5][6][7], topological insulators [8][9][10][11][12][13][14][15], graphene [16][17][18][19][20], carbon nanotubes [21,22], and semiconducting wires [23].…”

RKKY Interaction in Graphene at Finite Temperature

“…RKKY interaction has been investigated in materials of different nature such as disordered metals [4], superconductors [5][6][7], topological insulators [8][9][10][11][12][13][14][15], carbon nanotubes [16,17], semiconducting wires [18], in Weyl and Dirac semimetals [19][20][21][22][23][24], but most thoroughly in graphene . RKKY interaction in graphene is also the subject of the present publication.…”