Extensive neutron-scattering experiments have been performed on ${\mathrm{CuGeO}}_3$ single crystals to study the structural fluctuations in the neighborhood of the spin-Peierls transition at temperature ${\mathit{T}}_{\mathrm{SP}}$. We have succeeded in measuring the critical fluctuations up to a few K above ${\mathit{T}}_{\mathrm{SP}}$. The inverse correlation lengths κ associated with the structural fluctuations obtained along the [1 0 1] and [ 0 1 0] directions are consistent with those reported in the low-resolution diffuse x-ray-scattering measurements of Pouget et al. This agreement implies that the energy-integrated scattering function S(Q)=${\mathrm{\int }}_{\mathrm{-}\mathrm{\infty }}^{\mathrm{\infty }}$S(Q,ω)dω measured by diffuse x-ray scattering is dominated by structural fluctuations around ω=0, not by the softening of a zone-boundary phonon as expected in ordinary spin-Peierls systems. In order to examine the relationship between magnetic and structural fluctuations, further information on the magnetic excitations was collected. There remains considerable intensity above ${\mathit{T}}_{\mathrm{SP}}$ in the spin-excitation spectrum at (1/2 1 1/2), slowly decaying over a wide energy range (∼10 meV) and persisting up to about 50 K. We measured the magnetic dynamical structure factor S(Q,ω) over a wide range of energy and momentum space at temperatures of 4 K (≪${\mathit{T}}_{\mathrm{SP}}$) and 16 K (≳${\mathit{T}}_{\mathrm{SP}}$). The wave-vector dependent susceptibility χ(Q) deduced from the S(Q,ω) contour map at 16 K yields inverse correlation lengths consistent with those which we determined for the structural fluctuations. This indicates a strong symbiotic coupling between the magnetic and structural fluctuations near ${\mathit{T}}_{\mathrm{SP}}$ as expected. We speculate that the Cu ions are surrounded by strongly correlated spins and that the motions are heavily overdamped. The structural fluctuations towards dimerization are accompanied by magnetic correlations leading to a spin-singlet state.

The electronic orders in kagome materials have emerged as a fertile platform for studying exotic quantum states, and their intertwining with the unique kagome lattice geometry remains elusive. While various unconventional charge orders with broken symmetry is observed, the influence of kagome symmetry on magnetic order has so far not been directly observed. Here, using a high‐resolution magnetic force microscopy, it is, for the first time, observed a new lattice form of noncollinear spin textures in the kagome ferromagnet in zero magnetic field. Under the influence of the sixfold rotational symmetry of the kagome lattice, the spin textures are hexagonal in shape and can further form a honeycomb lattice structure. Subsequent thermal cycling measurements reveal that these spin textures transform into a non‐uniform in‐plane ferromagnetic ground state at low temperatures and can fully rebuild at elevated temperatures, showing a strong second‐order phase transition feature. Moreover, some out‐of‐plane magnetic moments persist at low temperatures, supporting the Kane–Mele scenario in explaining the emergence of the Dirac gap. The observations establish that the electronic properties, including both charge and spin orders, are strongly coupled with the kagome lattices.

Manipulating the direction of the magnetic field can induce various intriguing physical phenomena, such as the regulation of nematic phase and disappearance of the charge density wave. Conventional superconducting magnet-based scanning tunneling microscopes (STMs) operate with a perpendicular magnetic field direction to the sample surface, limiting their ability to investigate anisotropy of materials. Some STMs are integrated into vector magnets to achieve in-plane magnetic field conditions; however, these setups typically offer a maximum lateral magnetic field strength of less than 5 T, which is far below the critical magnetic field required for many materials. To explore the anisotropy of materials under in-plane magnetic fields exceeding 20 T, a new STM with small lateral tip–sample junction, which is capable of working in huge vibrational water-cooled magnets, is required. This paper presents an innovative design of such a small lateral size featured STM that is capable of operating under 35 T in-plane magnetic field conditions. The proposed STM utilizes an improved spider drive to drive the tip move in oblique upward direction, with the component of tip motion on the lateral direction being one-fifth of the vertical direction. With the novel design, the lateral size of the STM head is minimized to as small as 15 mm. The high rigidity of an independent scanner is proved by the high eigenfrequencies obtained through finite element analysis. The excellent imaging ability of our new STM are demonstrated by the high-quality atomic images of graphite and NbSe2 acquired under in-plane magnetic fields ranging from 0 to 35 T, illustrating the new STM’s high immunity to the magnetic field conditions. As far as known, this is the first STM capable of atomic imaging at magnetic field up to 35 T and capable of working at both 300 and 1.7 K low temperature; this is also the first water-cooled magnet STM capable of atomic imaging under 35 T magnetic field and huge vibrational conditions. Using this STM, we expect to investigate novel physical phenomena occurring under high in-plane magnetic fields.

Probing microscopic magnetic textures under ultra-high magnetic fields is critical for uncovering emergent quantum phenomena but remains experimentally challenging. Here, we present the first cryogenic magnetic force microscope (MFM) operating at temperatures below 3 K and magnetic fields up to 35 T in a water-cooled resistive magnet. A static exchange-gas helium cryostat provides a stable, chemically inert, and low-vibration cryogenic environment, while a nonmetallic MFM head and high-Q cantilever tips effectively suppress strong-field and mechanical disturbances. The frequency-shift noise is as low as ∼60 mHz at 33 T, well below typical magnetic signal amplitudes (>200 mHz), ensuring sustained high sensitivity throughout field ramping. Using this platform, we imaged field-driven magnetic textures in a multiferroic SrRuO3 film at 2.7 K from 0 to 35 T, revealing robust magnetic-domain behavior locked by ferroelastic domains. This work establishes a powerful platform for real-space imaging of quantum magnetism under extreme conditions.

Recently, there has been growing interest in using lightwave-driven scanning probe microscopy (LD-SPM) to break through the Abbe diffraction limit of focusing, yielding insight into various energy couplings and conversion processes and revealing the internal information of matter. We describe a compact and efficient optical cryostat designed for LD-SPM testing under magnetic fields. The exceptional multilayer radiation shielding insert (MRSI) forms an excellent temperature gradient when filled with heat conducting gas, which removes the requirement to install an optical window in the liquid helium cooling shell. This not only critically avoids the vibration and thermal drift caused by solid heat conduction but also minimizes light transmission loss. The application of gate valves and bellows allows a simpler and more effective replacement of the sample and working cell in the test cavity. ANSYS software is used for steady-state thermal analysis of the MRSI to obtain the temperature distribution and heat transfer rate, and the necessity of the flexible copper shielding strips is illustrated by the simulations. The topography and magnetic domain images of 45 nm-thick La_0.67Ca_0.33MnO₃ thin films on NdGaO₃(001) substrates under a magnetic field were obtained by a self-made lightwave-driven magnetic force microscope in this cryostat. The resolution and noise spectra during imaging reveal temperature stability and low vibration throughout the cryostat. The experience acquired during the development of this cryostat will help to establish cryostats of similar types for a variety of optic applications requiring the use of cryogenic temperatures.