Magnetoacoustic oscillations and the Fermi surface of LaAg

Quadrupolar ordered state at high fields in PrPb3

“…In the present work, in order to reveal the OPs of the ordered states in much higher fields than 5 T applied along the [110] direction, we performed neutron diffraction experiment at temperatures ranging from 50 mK to 0.8 K and in magnetic fields up to 14.5 T. Above 7 T, we have found field-induced magnetic reflections at q =(δ δ 0.5) (δ∼0.02) and its equivalents. The Q-dependence of their intensity indicates that the field induced antiferromagnetic component is perpendicular to the field, confirming that the quadrupolar OP of this new ordered phase should be of O 2 2 -type. In the fields of 3 T≤H≤7 T, we have also observed some reflections, for example, at q =(δ δ 0.5) (δ∼0.062) and its equivalents which were reported before.…”

“…We determined the amplitude of the sinusoidal structure to be 0.93(15) µ B . The fact that the antiferromagnetic component is perpendicular to the field suggests that the quadrupolar OP in the ordered phase should be the O 2 2 -type. [11] The uniform component of the magnetic moments at 10 T estimated from the field-enhanced intensity of the nuclear Bragg peaks was 1.52(20) µ B , being consistent with the results of the magnetization measurements.…”

“…On the other hand, when magnetic field was applied along the [011] direction, no superlattice reflection was observed on the (hkk) scattering plane (⊥H ) below 3 T, although weak reflections at q =(0.5 δ δ) (δ∼0.062) and its equivalents were observed only in the fields of 3 T<H<5 T at 80 mK. [12] From the analysis of the Q-dependence of the reflection intensity, the field-induced component is determined to be perpendicular to the field, suggesting that the OP should be of O 2 2 -type. [11] The O 2 2 -type OP was also suggested from the measurements of the field angle dependence of the transition temperature; a new phase characterized by the transition temperature T Q ' was observed in fields above 7 T in narrow field directions around the 110 axis.…”

“…PrPb 3 crystallizes in a simple AuCu 3 -type cubic structure, and has a Γ 3 non-Kramers doublet in the crystalline-electricalfield (CEF) ground state, with a magnetic Γ 4 triplet lying 15∼19 K above the ground state. [1,2] Since the Γ 3 doublet carries quadrupole moments such as O 0 2 and O 2 2 , PrPb 3 is a good candidate for a quadrupolar transition. Actually, at the temperature of T Q =0.4 K, a second order transition was observed with a lambda type anomaly in the spe-cific heat measurement.…”

“…[12] From the analysis of the Q-dependence of the reflection intensity, the field-induced component is determined to be perpendicular to the field, suggesting that the OP should be of O 2 2 -type. [11] The O 2 2 -type OP was also suggested from the measurements of the field angle dependence of the transition temperature; a new phase characterized by the transition temperature T Q ' was observed in fields above 7 T in narrow field directions around the 110 axis. [7] However, the ordered state in the magnetic fields above 5 T has not been revealed by a microscopic techniques yet.…”