NUM division - Publication Highlights

Datum
Bonfa et al

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 ...

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Dosenschloss

A precision mechanical masterpiece in miniature

With the discovery of a golden miniature box lock, an extraordinary and unique archaeological find was made in north-western Germany by a licensed detectorist.

The object represents an extremely reduced and valuable version of the provincial Roman box locks. These everyday objects were in general significantly larger and normally made either of iron, iron with silver or bronze bands or bronze.

 

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Fogh et al

Field-induced bound-state condensation and spin-nematic phase in SrCu2(BO3)2 revealed by neutron scattering up to 25.9 T

In quantum magnetic materials, ordered phases induced by an applied mag- netic field can be described as the Bose-Einstein condensation (BEC) of mag- non excitations. In the strongly frustrated system SrCu2(BO3)2, no clear magnon BEC could be observed, pointing to an alternative mechanism, but the high fields required to probe this physics have remained a barrier to detailed investigation.Here we exploit the first purpose-built high-field neutron scattering facility to measure ...

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Guguchia et al

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 CuOplane. Our results show a sixfold increase ...

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Park et al

Tetrahedral triple-Q magnetic ordering and large spontaneous Hall conductivity in the metallic triangular AFM Co1/3TaS2

The triangular lattice antiferromagnet (TLAF) has been the standard paradigm of frustrated magnetism for several decades. The most common magnetic ordering in insulating TLAFs is the 120° structure. However, a new triple-Q chiral ordering can emerge in metallic TLAFs, representing the short wave- length limit of magnetic skyrmion crystals. We report the metallic TLAF Co1/3TaS2 as the first example of tetrahedral triple-Q magnetic ordering with the associated topological Hall effect (non-zero σxy(H = 0)). We also ...

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Andriushin et al

Phonon Topology and Winding of Spectral Weight in Graphite

The topology of electronic and phonon band structures of graphene is well studied and known to exhibit a Dirac cone at the K point of the Brillouin zone. Here, we applied inelastic x-ray scattering (IXS) along with ab initio calculations to investigate phonon topology in graphite, the 3D analog of graphene. We identified a pair of modes that form a very weakly gapped linear anticrossing at the K point that can be essentially viewed as a Dirac cone approximant. The IXS intensity ...

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Singh et al

Skyrmion metamorphosis: Lattice transitions of hybrid skyrmions in a polar magnet

Magnetic skyrmions, with their distinctive vortex-like magnetic spin configurations, continue to intrigue researchers due to their potential applications in nanoscience and technology. Traditionally skyrmions form two-dimensional hexagonal close-packed lattices, with the skyrmions themselves displaying one of just two types of internal magnetization texture known as Bloch- or Néel-type. Recent theories hinted at the prospect of reconfigurable transitions between skyrmion phases of different lattice types and internal textures. Until now, experimental evidence supporting such theories has been scarce.

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Khasanov et al - 2

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 ...

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