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Abstract A polymorph of Cu2OSeO3 with the distorted kagome lattice is successfully obtained using the high‐pressure synthesis technique (Cu2OSeO3‐HP). The structural analysis using X‐ray and neutron powder diffraction suggests that the tetrahedral Cu2+ clusters [similar to those in Cu2OSeO3 ambient‐pressure phase (Cu2OSeO3‐AP)] exist in Cu2OSeO3‐HP but with three symmetry inequivalent sites. No structural change is observed between 1.5 K and the room temperature. The complex magnetic H‐T phase diagram is established based on the temperature‐ and field‐dependent magnetization data, indicating two distinct antiferromagnetic phases at low and intermediate temperatures, in addition to the higher‐temperature spin‐glass‐like phase. The low temperature phase is identified by neutron powder diffraction refinements as a canted noncollinear antiferromagnetic order with a weak ferromagnetic component along the b‐axis. Size of the refined ordered moment is ≈1.00(4) µB in Cu2OSeO3‐HP, indicating a large enhancement compared to that of Cu2OSeO3‐AP (≈0.61 µB). By applying a uniaxial stress, finite enhancement of weak ferromagnetic component in the noncollinear antiferromagnetic phase in Cu2OSeO3‐HP is observed, which is the clear evidence of the piezomagnetic effect. Interestingly, the sign of the induced magnetization changes on heating from the low‐temperature to the intermediate‐temperature phases, indicating a novel piezomagnetic switching effect in this compound.

We have investigated magnetic properties of the rare-earth based intermetallic compound Yb3Ni11Ge4.63 (YNG), where Yb3+ ions form a breathing-kagome lattice. Single-site 4 f electron wavefunctions of the ground-state doublet are deduced from magnetization and heat capacity measurements. The Weiss temperatures are quite anisotropic as Θa = -0.01(2)K (H ‖ a) and Θc = -0.67(2)K (H ‖ c), indicating Ising-like spin-spin interactions dominating in this compound. Low-temperature neutron diffraction confirms absence of magnetic Bragg peaks down to 0.05 K, whereas enhancement of broad peaks below 0.8K was observed, a signature of short-range spin correlations. Competing interactions on the breathing-kagome lattice would suppress a magnetic long-range order in YNG. [ABSTRACT FROM AUTHOR]

A tiny adiabatic-demagnetization refrigerator (T-ADR) has been developed for a commercial superconducting quantum interference device magnetometer [Magnetic Property Measurement System (MPMS) from Quantum Design]. The whole T-ADR system is fit in a cylindrical space of diameter 8.5 mm and length 250 mm, and can be inserted into the narrow sample tube of MPMS. A sorption pump is self-contained in T-ADR, and hence no complex gas handling system is necessary. With the single crystalline Gd3Ga5O12 garnet (~2 g) used as a magnetic refrigerant, the routinely achievable lowest temperature is ~0.56 K. The lower detection limit for a magnetization anomaly is ~1 × 10-7 emu, estimated from fluctuation of the measured magnetization. The background level is ~5 × 10-5 emu below 2 K at H = 100 Oe, which is largely attributable to a contaminating paramagnetic signal from the magnetic refrigerant. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility and neutron powder diffraction experiments have been performed on the noncentrosymmetric ternary compound Pr5Ru3Al2. The previously reported ferromagnetic transition at 24K was not detected in our improved-quality samples. Instead, magnetic ordering was observed in the DC magnetic susceptibility at Tc ≃ 3:8 K. The neutron powder diffraction experiment further indicates that an incommensurate magnetic structure is established below Tc with the magnetic modulation vector q ≃ (066; 0:066; 0:066) (r.l.u.). A candidate for the magnetic structure is proposed using representation analysis. [ABSTRACT FROM AUTHOR]

A small angle neutron inelastic scattering measurement has been performed to study the magnon dispersion relation in the field-induced ferromagnetic phase of the noncentrosymmetric binary compound MnSi. For the magnons propagating parallel or antiparallel to the external magnetic field, we experimentally confirmed that the dispersion relation is asymmetrically shifted along the magnetic field direction. This magnon dispersion shift is attributed to the relativistic Dzyaloshinskii-Moriya interaction, which is finite in noncentrosymmetric magnets, such as MnSi. The shift direction is found to be switchable by reversing the external magnetic field direction. [ABSTRACT FROM AUTHOR]

Long-range noncollinear all-in-all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd2Os2O7 using resonant magnetic microdiffraction at the Os L3 edge. Two different antiferromagnetic domains related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected-yet unobserved sofar-in the all-in-all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure. [ABSTRACT FROM AUTHOR]

Small angle neutron scattering measurements have been performed to study the thermodynamic stability of skyrmion-lattice phases in Cu2OSeO3. We found that the two distinct skyrmion-lattice phases [SkX(1) and SkX(2) phases] can be stabilized through different thermal histories; by cooling from the paramagnetic phase under finite magnetic field, the SkX(2) phase is selected. On the other hand, the 30°-rotated SkX(1) phase becomes dominant by heating the sample from the ordered conical phase under finite field. This difference in stabilization is surprisingly similar to the irreversibility observed in spin glasses. The zero-field cooling results in the coexistence of the two phases. It is further found that once one of the skyrmion-lattice phases is formed, it is hardly destabilized. This indicates unusual thermal stability of the two skyrmion-lattice phases originating from an unexpectedly large energy barrier between them. [ABSTRACT FROM AUTHOR]