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arXiv · 1909.07819

Strong quantum fluctuations due to competition between magnetic phases in a pyrochlore iridate

Henrik Jacobsen·Cameron D. Dashwood·Elsa Lhotel·Dmitry Khalyavin·Pascal Manuel·Ross Stewart·Dharmalingam Prabhakaran·Desmond F. McMorrow·Andrew. T. Boothroyd
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Abstract

We report neutron diffraction measurements of the magnetic structures in two pyrochlore iridates, Yb2Ir2O7 and Lu2Ir2O7. Both samples exhibit the all-in-all-out magnetic structure on the Ir4+ sites below TN~ 150,K, with a low temperature moment of around 0.45 muB/Ir. Below 2\,K, the Yb moments in Yb2Ir2O7 begin to order ferromagnetically. However, even at 40 mK the ordered moment is only 0.57(3)muB/Yb, well below the saturated moment of the ground state doublet of Yb3+ (1.9 muB/Yb), deduced from magnetization measurements and from a refined model of the crystal field environment, and also significantly smaller than the ordered moment of Yb in Yb2Ti2O7 (0.9 muB/Yb). A mean-field analysis shows that the reduced moment on Yb is a consequence of enhanced phase competition caused by coupling to the all-in-all-out magnetic order on the Ir sublattice.

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Henrik Jacobsen, Cameron D. Dashwood, Elsa Lhotel, Dmitry Khalyavin, Pascal Manuel, Ross Stewart, Dharmalingam Prabhakaran, Desmond F. McMorrow, Andrew. T. Boothroyd. 2020-02-13. Strong quantum fluctuations due to competition between magnetic phases in a pyrochlore iridate. https://doi.org/10.1103/physrevb.101.104404

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