Steven Disseler

Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures

Magnetic topological insulators such as Cr-doped (Bi,Sb)2Te3 provide a platform for the realization of versatile time-reversal symmetry-breaking physics. By constructing heterostructures exhibiting Néel order in an antiferromagnetic CrSb and ferromagnetic order in Cr-doped (Bi,Sb)2Te3, we realize emergent interfacial magnetic phenomena which can be tailored through artificial structural engineering. Through deliberate geometrical design of heterostructures and superlattices, we demonstrate the use of antiferromagnetic exchange coupling in manipulating the magnetic properties of magnetic topological insulators. Proximity effects are shown to induce an interfacial spin texture modulation and establish an effective long-range exchange coupling mediated by antiferromagnetism, which significantly enhances the magnetic ordering temperature in the superlattice. This work provides a new framework on integrating topological insulators with antiferromagnetic materials and unveils new avenues towards dissipationless topological antiferromagnetic spintronics.

Magnetic order in the pyrochlore iridates A(2)Ir(2)O(7) (A = Y, Yb)

We present results from muon spin relaxation/rotation, magnetization, neutron scattering, and transport measurements on polycrystalline samples of the pyrochlore iridates Y2Ir2O7 (Y-227) and Yb2Ir2O7 (Yb-227). Well-defined spontaneous oscillations of the muon asymmetry are observed together with hysteretic behavior in magnetization below 130 K in Yb-227, indicative of commensurate long-range magnetic order. Similar oscillations are observed in Y-227 below 150 K; however, the onset of hysteretic magnetization at T = 190 K indicates a transition to an intermediate state lacking long-range order as observed in Nd-227. Our results also show that insulating members of the iridate family have nearly identical magnetic ground states, and that the presence of magnetic A-site species does not play any significant role in altering the ground-state properties.

Multiferroicity in doped hexagonal LuFeO3

Neutron scattering techniques are used to investigate the crystalline and magnetic structure of LuFe

Magnetic order and the electronic ground state in the pyrochlore iridate Nd2Ir2O7

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Spin ordering and electronic texture in the bilayer iridate Sr3Ir2O7

Mn

Magnetization and Hall effect studies on the pyrochlore iridate Nd2Ir2O7

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Competing interactions and magnetic frustration in Yb4LiGe4

O

One Dimensional(1D)-to-2D Crossover of Spin Correlations in the 3D Magnet ZnMn2O4.

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Electronic nature of the lock-in magnetic transition in CeXAl4Si2

in bulk polycrystalline form. We find that the crystalline structure is described by the hexagonal P6

Yb4LiGe4 – A Yb mixed valent Zintl phase with strong electronic correlations

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