Scientific Highlights
Pauling Entropy, Metastability, and Equilibrium in Dy2Ti2O7 Spin Ice
Determining the fate of the Pauling entropy in the classical spin ice material Dy2Ti2O7 with respect to the third law of thermodynamics has become an important test case for understanding the existence and stability of ice-rule states in general. The standard model of spin ice—the dipolar spin ice model—predicts an ordering transition at T ≈ 0.15K, but recent experiments by Pomaranski et al.
Direct electric field control of the skyrmion phase in a magnetoelectric insulator
Magnetic skyrmions are topologically protected spin-whirls currently considered as promising for use in ultra-dense memory devices. Towards achieving this goal, exploration of the skyrmion phase response and under external stimuli is urgently required.
Experimental signatures of emergent quantum electrodynamics in Pr2Hf2O7
In a quantum spin liquid, the magnetic moments of the constituent electron spins evade classical long-range order to form an exotic state that is quantum entangled and coherent over macroscopic length scales. Such phases offer promising perspectives for device applications in quantum information technologies, and their study can reveal new physics in quantum matter.
Complementary Response of Static Spin-Stripe Order and Superconductivity to Nonmagnetic Impurities in Cuprates
We report muon-spin rotation and neutron-scattering experiments on nonmagnetic Zn impurity effects on the static spin-stripe order and superconductivity of the La214 cuprates. Remarkably, it was found that, for samples with hole doping x ≈ 1/8, the spin-stripe ordering temperature Tso decreases linearly with Zn doping y and disappears at y ≈ 4%, demonstrating a high sensitivity of static spin-stripe order to impurities within a CuO2 plane.
4-spin plaquette singlet state in the Shastry–Sutherland compound SrCu2(BO3)2
The study of interacting spin systems is of fundamental importance for modern condensed-matter physics. On frustrated lattices, magnetic exchange interactions cannot be simultaneously satisfied, and often give rise to competing exotic ground states. The frustrated two-dimensional Shastry–Sutherland lattice realized by SrCu2(BO3)2 is an important test to our understanding of quantum magnetism.
Coupled multiferroic domain switching in the canted conical spin spiral system Mn2GeO4
Despite remarkable progress in developing multifunctional materials, spin-driven ferro-electrics featuring both spontaneous magnetization and electric polarization are still rare. Among such ferromagnetic ferroelectrics are conical spin spiral magnets with a simultaneous reversal of magnetization and electric polarization that is still little understood. Such materials can feature various multiferroic domains that complicates their study.
Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena, including the realization of chiral Weyl fermions as quasiparticles in the bulk and the formation of Fermi arc states on the surfaces.
New magnetic phase in the nickelate perovskite TlNiO3
The RNiO3 perovskites are known to order antiferromagnetically below a material-dependent Néel temperature TN. We report experimental evidence indicating the existence of a second magnetically ordered phase in TlNiO3 above TN = 104K, obtained using nuclear magnetic resonance and muon spin rotation spectroscopy.
Suppression of magnetic excitations near the surface of the topological Kondo insulator SmB6
We present a detailed investigation of the temperature and depth dependence of the magnetic properties of the three-dimensional topological Kondo insulator SmB6, in particular, near its surface. We find that local magnetic field fluctuations detected in the bulk are suppressed rapidly with decreasing depths, disappearing almost completely at the surface.