Competing magnetic phases and field-induced dynamics in DyRuAsO

Abstract

Analysis of neutron diffraction, dc magnetization, ac magnetic susceptibility, heat capacity, and electrical resistivity for DyRuAsO in an applied magnetic field are presented at temperatures near and below those at which the structural distortion (TS = 25 K) and subsequent magnetic ordering (TN = 10.5 K) take place. Powder neutron diffraction is used to determine the antiferromagnetic order of Dy moments of magnitude 7.6(1) µB in the absence of a magnetic field, and demonstrate the reorientation of the moments into a ferromagnetic configuration upon application of a magnetic field. Dy magnetism is identified as the driving force for the structural distortion. The magnetic structure of analogous TbRuAsO is also reported. Competition between the two magnetically ordered states in DyRuAsO is found to produce unusual physical properties in applied magnetic fields at low temperature. An additional phase transition near T * = 3 K is observed in heat capacity and other properties in fields 3 T. Magnetic fields of this magnitude also induce spinglass-like behavior including thermal and magnetic hysteresis, divergence of zero-field-cooled and field-cooled magnetization, frequency dependent anomalies in ac magnetic susceptibility, and slow relaxation of the magnetization. This is remarkable since DyRuAsO is a stoichiometric material with no disorder detected by neutron diffraction, and suggests analogies with spin-ice compounds and related materials with strong geometric frustration.

Short- and long-range magnetic order in LaMnAsO

“…Doping other transition metals on the Fe site can induce superconductivity [14], while full replacement of Fe produces diverse and interesting phenomena. These include giant magnetoresistance and rare-earth magnetism in LnMnAsO [15][16][17][18], itinerant fer- * McGuireMA@ornl.gov romagnetism in LnCoAsO [19][20][21][22], low temperature superconductivity and Kondo physics in LnNiAsO [23][24][25][26], and glassy magnetism in LnRuAsO [27].…”

Co-evolution of Microstructure and Magnetic Properties in Magnetically Aligned MnBi-Bi Composites

“…MnBi is a strong room temperature ferromagnet with very favorable properties in which the large Mn magnetic moments are oriented along the c-axis of the NiAs-type hexagonal structure [1,4]. Previous reports indicate the Mn-Bi phase diagram can be exploited to produce elongated MnBi grains preferentially orientated within a Bi single crystal matrix, producing a material with strongly anisotropic magnetic susceptibility [5].…”

Superconductivity at 7.8 K in the ternary LaRu2As2 compound

“…The 122-type BaRu 2 As 2 and SrRu 2 As 2 compounds with ThCr 2 Si 2 -type structure were found to be metallic, non-superconducting and show no signature of long-range magnetic ordering with measurements down to 1.8 K [16]. The 1111-type LnRuAsO (Ln = rare earth elements) compounds were also carefully investigated for structural and physical properties, and antiferromagnetic to ferromagnetic order transition was found in some of these compounds, while no superconductivity was ever reported, even in the F-doped materials [17][18][19][20][21]. Besides, for other iron-free pnictides with ThCr 2 Si 2 -type crystal structure, superconductivity was also reported in SrNi 2 As 2 , BaNi 2 As 2 , SrIr 2 As 2 , CaPd 2 As 2 , BaPd 2 As 2 , LaPd 2 As 2 , etc., while their T c is all lower than 5 K [22][23][24][25][26][27].…”