Spin textures induced by quenched disorder in a reentrant spin glass: Vortices versus "frustrated" skyrmions

1.5 GPa compact double-wall clamp cell for SANS and NSE studies at low temperatures and high magnetic fields

We have developed and realised a compact high-pressure clamp cell of the piston-cylinder type for Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectroscopy measurements. The cell can pressurise φ5 mm samples up to 1.5 GPa. It is non-magnetic, produces a sufficiently low and flat SANS background with a relatively good...

New magnetic phase of the chiral skyrmion material Cu₂OSeO₃

The lack of inversion symmetry in the crystal lattice of magnetic materials gives rise to complex noncollinear spin orders through interactions of a relativistic nature, resulting in interesting physical phenomena, such as emergent electromagnetism. Studies of cubic chiral magnets revealed a universal magnetic phase diagram composed of...

Reorientations, relaxations, metastabilities, and multidomains of skyrmion lattices

Magnetic skyrmions are nanosized topologically protected spin textures with particlelike properties. They can form lattices perpendicular to the magnetic field, and the orientation of these skyrmion lattices with respect to the crystallographic lattice is governed by spin-orbit coupling. By performing small-angle neutron scattering measurements,...

Universality of the helimagnetic transition in cubic chiral magnets: Small angle neutron scattering and neutron spin echo spectroscopy studies of FeCoSi

We present a comprehensive Small Angle Neutron Scattering (SANS) and Neutron Spin Echo Spectroscopy (NSE) study of the structural and dynamical aspects of the helimagnetic transition in Fe_1-xCo_xSi with x = 0.30. In contrast to the sharp transition observed in the archetype chiral magnet MnSi, the transition in Fe<sub>1-x<...

Magnetic Fluctuations, Precursor Phenomena, and Phase Transition in MnSi under a Magnetic Field

The reference chiral helimagnet MnSi is the first system where Skyrmion lattice correlations have been reported. At a zero magnetic field the transition at TC to the helimagnetic state is of first order. Above TC, in a region dominated by precursor phenomena, neutron scattering shows the buildup of strong chiral fluctuating correlations over...

Magnetic relaxation phenomena in the chiral magnet Fe1−xCoxSi: An ac susceptibility study

We present a systematic study of the ac susceptibility of the chiral magnet Fe1−xCoxSi with x=0.30 covering four orders of magnitude in frequencies from 0.1 Hz to 1 kHz, with particular emphasis to the pronounced history dependence. Characteristic relaxation times ranging from a few milliseconds to tens of seconds are observed around the...

How to polarise all neutrons in one beam: A high performance polariser and neutron transport system

Polarised neutron beams are used in disciplines as diverse as magnetism,soft matter or biology. However, most of these applications often suffer from low flux also because the existing neutron polarising methods imply the filtering of one of the spin states, with a transmission of 50% at maximum. With the purpose of using all neutrons that...

Extended skyrmion lattice scattering and long-time memory in the chiral magnet Fe1-xCoxSi

Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet Fe1-xCoxSi with x=0.3 reveal a pronounced effect of the magnetic history and cooling rates on the magnetic phase diagram. The extracted phase diagrams are qualitatively different for zero and field cooling and reveal a metastable skyrmion lattice...

Phase diagram and magnetic relaxation phenomena in Cu2OSeO3

We present an investigation of the magnetic-field-temperature phase diagram of Cu2OSeO3 based on dc magnetization and ac susceptibility measurements covering a broad frequency range of four orders of magnitude, from very low frequencies reaching 0.1 Hz up to 1 kHz. The experiments were performed in the vicinity of Tc=58.2 K and around the...

Design and performance of a novel neutron powder diffractometer: PEARL at TU Delft

The performance of the new neutron powder diffraction instrument PEARL that is installed at the research reactor of Delft University of Technology is reported. It is based on the optimization concepts developed by Cussen [Nucl. Instrum. Methods Phys. Res. Sect. A (2007), 583, 394-406], which lead to high performance competing with existing...

Quasielastic neutron scattering experiment on water using TOFLAR (Time Of Flight and LARmor precession) technique at SNS

We present the results of the first TOFLAR (Time Of Flight and LARmor precession) experiment with a Larmor modulation device positioned after the sample. Using a setup based on the configuration of the SNS-NSE spectrometer (Spallation Neutron Source, USA), we did TOFLAR measurements on water at 5 and 20 degree Celsius, analyzed the spectra, and...

Magnetic fluctuations and correlations in MnSi: Evidence for a chiral skyrmion spin liquid phase

We present a comprehensive analysis of high-resolution neutron scattering data involving neutron spin echo spectroscopy and spherical polarimetry, which confirm the first-order nature of the helical transition in MnSi. The experiments reveal the existence of a totally chiral dynamic phase in a very narrow temperature range above TC. This...

Neutrons with a twist!

Chiral Paramagnetic Skyrmion-like Phase in MnSi

We present a comprehensive study of chiral fluctuations in the reference helimagnet MnSi by polarized neutron scattering and neutron spin echo spectroscopy, which reveals the existence of a completely left-handed and dynamically disordered phase. This phase may be identified as a spontaneous Skyrmion phase: it appears in a limited temperature...