Scientific Highlights
Introduction to Muon Spin Spectroscopy
Alex Amato and Elvezio Morenzoni (both NUM) have published a new textbook entitled 'Introduction to Muon Spin Spectroscopy: Applications to Solid State and Material Sciences'. The book is ideal for a first course in muon spin spectroscopy (µSR), comes enriched with exercises and solutions to master the subject and includes practical examples to quantify key experimental parameters.
Phonon promoted charge density wave in topological kagome metal ScV6Sn6
Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention, yet their origin remains a topic of debate. The discovery of ScV6Sn6, a bilayer kagome metal featuring an intriguing √3 × √3 × √3 CDW order, offers a novel platform to explore the underlying mechanism behind the unconventional CDW. Here we combine ...
Tuning of the flat band and its impact on superconductivity in Mo5Si3−xPx
The superconductivity in systems containing dispersionless (flat) bands is seemingly paradoxical, as traditional Bardeen-Cooper-Schrieffer theory requires an infinite enhancement of the carrier masses. However, the combination of flat and steep (dispersive) bands within the multiple band scenario might boost superconducting responses, potentially explaining high-temperature superconductivity in cuprates and metal hydrides. Here, we report ...
Interface-induced superconductivity in magnetic topological insulators
One of the recipes for realizing topological superconductivity calls for interfacing a topological insulator with a superconductor. In a variant of that approach, Yi et al. grew a heterostructure consisting of layers of a magnetic topological insulator, (Bi,Sb)2Te3 doped with chromium, and antiferromagnetic iron telluride. Neither of these materials is superconducting, but iron telluride is a parent compound for a family of iron-based superconductors. Interfacing the layers led to the appearance of superconductivity in the presence of ferromagnetism and topological band structure. This combination of properties makes the heterostructure a promising, although not yet proven, platform for observing chiral topological superconductivity.
Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide
Magnetostriction results from the coupling between magnetic and elastic degrees of freedom. Though it is associated with a relatively small energy, we show that it plays an important role in determining the site of an implanted muon, so that the energetically favorable site can switch on crossing a magnetic phase transition. This surprising effect is demonstrated in the cubic rocksalt antiferromagnet MnO which undergoes a magnetostriction-driven rhombohedral distortion at the Néel temperature TN = 118 K. Above TN ...
Designing the stripe-ordered cuprate phase diagram through uniaxial-stress
Understanding the degree to which charge-stripe, spin-stripe, and superconducting orders compete/coexist is paramount for elucidating the microscopic pairing mechanism in the cuprate high-temperature superconductors. We explore the tunability of magnetism, superconductivity, and crystal structure in the stripe phase of the cuprate La2−xBaxCuO4, by employing complementary techniques under compressive uniaxial stress in the CuO2 plane. Our results show a sixfold increase ...
In-Plane Magnetic Penetration Depth in Sr2 RuO4 : Muon-Spin Rotation and Relaxation Study
We report on measurements of the in-plane magnetic penetration depth (λab) in single crystals of Sr2RuO4 down to ≃0.015 K by means of muon-spin rotation-relaxation. The linear temperature dependence of λ−2ab for T≲0.7 K suggests the presence of nodes in the superconducting gap. This statement is further substantiated by observation of the Volovik effect, i.e., the reduction of λ−2ab as a function of the applied magnetic field. The experimental zero-field ...
Hidden magnetism uncovered in a charge ordered bilayer kagome material ScV6Sn6
Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered kagome material ScV6Sn6 does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe an enhancement ...
Kondo screening in a Majorana metal
Kondo impurities provide a nontrivial probe to unravel the character of the excitations of a quantum spin liquid. In the S = 1/2 Kitaev model on the honeycomb lattice, Kondo impurities embedded in the spin-liquid host can be screened by itinerant Majorana fermions via gauge-flux binding. Here, we report experimental signatures of metallic-like Kondo screening at intermediate temperatures in the Kitaev honeycomb material α-RuCl3 with dilute Cr3+ (S = 3/2) impurities.