Magnetism and magnetic order in the pyrochlore iridates in the insulator-to-metal crossover region

13th International Conference on Muon Spin Rotation, Relaxation and Resonance

Graf, M.J.^1 ; Disseler, S.M.^2 ; Dhital, C.^1 ; Hogan, T.^1 ; Bojko, M.^1 ; Amato, A.^3 ; Luetkens, H.^3 ; Baines, C.^3 ; Margineda, D.^4 ; Giblin, S.R.^4 ; Jura, M.^5 ; Wilson, S.D.^1,6

Department of Physics, Boston College, Chestnut Hill

MA

02467, United States^1

Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg

MD

20899, United States^2

Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI

CH-5232, Switzerland^3

School of Physics and Astronomy, Cardiff University, Cardiff

CF24 3AA, United Kingdom^4

Rutherford Appleton Laboratory, Didcot, Oxfordshire

OX11 0QX, United Kingdom^5

Materials Department, University of California Santa Barbara, Santa Barbara

CA

93106, United States^6

关键词: Characteristic frequencies;    Crossover regions;    Insulator to metal;    Long range magnetic order;    Lower temperatures;    Magnetic anomalies;    Muon spin relaxation;    Weakly conducting;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/551/1/012020/pdf
DOI  :  10.1088/1742-6596/551/1/012020

来源: IOP

【 摘 要 】

We present resistivity, magnetization, and zero field muon spin relaxation (μSR) data for the pyrochlore iridate materials Nd2-xCaxIr2O7 (x 0, 0.06, and 0.10) and Sm2Ir2O7. While Nd2Ir2O7 (Nd227) is weakly conducting, Sm2Ir2O7 (Sm227) has a slowly diverging resistivity at low temperature. Nd227 and Sm227 exhibit magnetic anomalies at TM 105K and 137K, respectively. However, zero-field μSR measurements show that long-range magnetic order of the Ir4+sublattice sets in at much lower temperatures (TLRO ∼ 8K for Nd227 and 70K for Sm227); both materials show heavily damped muon precession with a characteristic frequency near 9 MHz. The magnetic anomaly at TM in Nd227 is not significantly affected by the introduction of hole carriers by Ca-substitution in the conducting Nd2-xCaxIr2O7 samples, but the muon precession is fully suppressed for both.