DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Europium c -axis ferromagnetism in Eu ( Co 1 - x Ni x ) 2 - y As 2 : A single-crystal neutron diffraction study

Journal Article · · Physical Review. B

Here we report neutron diffraction results for the body-centered-tetragonal series Eu⁢(Co1-x⁢Nix)2-yAs2, x=0.10, 0.20, 0.42, and 0.82, y≤0.10, that detail changes to the magnetic ordering with nominal hole doping. We report the antiferromagnetic (AFM) propagation vectors, magnetic transition temperatures, and the ordered magnetic moments. We find a nonmonotonic change of the AFM propagation vector with x, with a minimum occurring at the tetragonal to collapsed-tetragonal phase crossover. For x=0.10 and 0.82 we find c-axis helix ordering of the Eu magnetic moments (spins) similar to x=0 and 1, with the spins oriented within the ab-plane. For x=0.20 and 0.42 we find higher-temperature c-axis ferromagnetic (FM) order and lower-temperature c-axis cone order. Using the extinction conditions for the space group, we discovered that the Eu spins are ordered in the higher-temperature c-axis FM phase for intermediate values of x, contrary to a previous report suggesting only Co/Ni spin ordering. Although we cannot directly confirm that the Co/Ni spins are also ordered, we suggest that c-axis itinerant-FM ordering of the Co/Ni spins could provide a molecular field that drives FM ordering of the Eu spins, which in turn provides the anisotropy for the lower-temperature c-axis cone order.

Research Organization:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
Grant/Contract Number:
AC02-07CH11358
OSTI ID:
2367350
Report Number(s):
IS-J--11,335
Journal Information:
Physical Review. B, Journal Name: Physical Review. B Journal Issue: 17 Vol. 109; ISSN 2469-9950
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (42)

Spin Fluctuation Theory of Itinerant Electron Magnetism book January 2013
Spin Fluctuations in Itinerant Electron Magnetism book January 1985
Ternary lanthanoid-transition metal pnictides with ThCr2Si2-type structure journal April 1978
Recent advances in magnetic structure determination by neutron powder diffraction journal October 1993
Making and Breaking Bonds in the Solid State: The ThCr 2 Si 2 Structure journal September 1985
A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo 2 As 2 (A = Eu and Ca) journal February 2016
Iron pnictides and chalcogenides: a new paradigm for superconductivity journal January 2022
The puzzle of high temperature superconductivity in layered iron pnictides and chalcogenides journal October 2010
Europium-based iron pnictides: a unique laboratory for magnetism, superconductivity and structural effects journal November 2016
Short-range ferromagnetic order due to Ir substitutions in single-crystalline Ba(Co 1 x Ir x ) 2 As 2 (0 x 0.25) journal December 2020
Competing magnetic phases and itinerant magnetic frustration in SrCo 2 As 2 journal August 2019
Helical antiferromagnetic ordering in EuNi 1.95 As 2 single crystals journal September 2019
Flat-band magnetism and helical magnetic order in Ni-doped SrCo 2 As 2 journal September 2019
Carrier tuning of Stoner ferromagnetism in ThCr2Si2 -structure cobalt arsenides journal December 2021
Renormalized behavior and proximity of BaCo 2 As 2 to a magnetic quantum critical point journal January 2009
Evidence for a reentrant superconducting state in EuFe 2 As 2 under pressure journal June 2009
Magnetic structure of EuFe 2 As 2 as determined by resonant x-ray scattering journal October 2009
Magnetic structure of EuFe 2 As 2 determined by single-crystal neutron diffraction journal November 2009
Superconductivity and local-moment magnetism in Eu ( Fe 0.89 Co 0.11 ) 2 As 2 journal November 2009
Interplay of antiferromagnetism, ferromagnetism, and superconductivity in EuFe 2 (As 1 − x P x ) 2 single crystals journal February 2011
Magnetic exchange interactions in BaMn 2 As 2 : A case study of the J 1 - J 2 - J c Heisenberg model journal September 2011
Crystal and magnetic structure of CaCo 1.86 As 2 studied by x-ray and neutron diffraction journal November 2013
Crystallography and physical properties of BaCo 2 As 2 , Ba 0.94 K 0.06 Co 2 As 2 , and Ba 0.78 K 0.22 Co 2 As 2 journal August 2014
Suppression of magnetic order in CaCo 1.86 As 2 with Fe substitution: Magnetization, neutron diffraction, and x-ray diffraction studies of Ca ( Co 1 − x Fe x ) y As 2 journal February 2017
NMR determination of an incommensurate helical antiferromagnetic structure in EuCo 2 As 2 journal May 2017
Enhanced moments of Eu in single crystals of the metallic helical antiferromagnet EuCo 2 − y As 2 journal April 2018
Spiral magnetic ordering of the Eu moments in EuNi 2 As 2 journal January 2019
Magnetic structure and magnetization of z -axis helical Heisenberg antiferromagnets with XY anisotropy in high magnetic fields transverse to the helix axis at zero temperature journal June 2019
Magnetic Susceptibility of Collinear and Noncollinear Heisenberg Antiferromagnets journal August 2012
Coexistence of Half-Metallic Itinerant Ferromagnetism with Local-Moment Antiferromagnetism in Ba 0.60 K 0.40 Mn 2 As 2 journal July 2013
Stripe Antiferromagnetic Spin Fluctuations in SrCo 2 As 2 journal October 2013
Itinerant Ferromagnetism in the As 4 p Conduction Band of Ba 0.6 K 0.4 Mn 2 As 2 Identified by X-Ray Magnetic Circular Dichroism journal May 2015
Effective One-Dimensional Coupling in the Highly Frustrated Square-Lattice Itinerant Magnet CaCo 2 − y As 2 journal October 2017
Coexistence of Ferromagnetic and Stripe Antiferromagnetic Spin Fluctuations in SrCo 2 As 2 journal March 2019
Pressure-induced Transition of the Sublattice Magnetization in EuCo 2 P 2 : Change from Local Moment Eu ( 4 f ) to Itinerant Co ( 3 d ) Magnetism journal January 1998
Magnetic phase transitions in Eu( Co 1 − x Ni x ) 2 − y As 2 single crystals journal August 2020
Superconductivity in iron compounds journal December 2011
Antiferromagnetic order and spin dynamics in iron-based superconductors journal August 2015
VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data journal October 2011
Mag2Pol : a program for the analysis of spherical neutron polarimetry, flipping ratio and integrated intensity data journal February 2019
FeAs-Based Superconductivity: A Case Study of the Effects of Transition Metal Doping on BaFe 2 As 2 journal August 2010
Bilbao Crystallographic Server: I. Databases and crystallographic computing programs journal January 2006