Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

Abstract

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores Malkin, B. Z.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Dhalenne, G.; Zakirov, A. R. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractThe experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R 2 Ti 2 O 7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

Structural and magnetic investigations of single-crystalline neodymium zirconate pyrochloreNd2Zr2O7

“…μ = −μ B (k L + 2S) is the magnetic moment of a Nd 3+ ion. (L and S are the electronic orbital and spin moments, respectively, and k is the orbital reduction factor [49].) The local magnetic field affecting the Nd 3+ ions, H loc = H + H exch + H dip − H D , involves the external field H, the exchange and dipolar fields H exch and H dip , respectively, corresponding to anisotropic exchange and magnetic dipolar interactions between the Nd 3+ ions that are considered within the self-consistent field approximation, and the demagnetizing field H D = 4πN M/3, where N is the demagnetizing factor, M = n m n /ν is the magnetization, and ν = a 3 /4 is the unit cell volume.…”

“…The exchange interaction is assumed to be nonzero for the nearest-neighbor Nd 3+ ions only. In particular, the exchange interaction between the ions with radius vectors r 1 = ( )a is approximated by [49] …”

“…However, the CF splittings of the ground multiplets 4 The temperature dependence of the dc susceptibility was calculated using the corresponding expression presented in Ref. [49], the results of the calculations are shown in Fig. 2(b).…”

Vindication ofYb2Ti2O7as a Model Exchange Quantum Spin Ice

“…Also, should a QSI state be solely defined by whether or not a QSL state is realized? While a QSI picture has been suggested relevant to the QSL behavior in Tb 2 Ti 2 O 7 [3] and Pr 2 M 2 O 7 [4], intense experimental [14][15][16][17][18][19][20][21] and theoretical [16][17][18][21][22][23][24][25][26] interest has recently turned to Yb 2 Ti 2 O 7 (YbTO), which has been argued to be on the verge of realizing a QSL originating from QSI physics. In fact, the combination of (i) an unexplained transition at T c ∼ 0.24 K [14,27], (ii) the controversial evidence for long-range order below T c [28,29] and (iii) the high sensitivity of the low-temperature (T < 300 mK) behavior to sample preparation conditions [19,20] are all tantalizing evidence that YbTO has a fragile and perhaps unconventional ground state.…”

Spin dynamics in highly frustrated pyrochlore magnets

“…K i, j denotes an anisotropic exchange coupling tensor, defined in the ( a, b, c) frame attached to the Er 3+ −Er 3+ bonds [27]. It consists in a symmetric part with 3 parameters K a,b,c , and an antisymmetric (Dzyaloshinskii-Moriya) part with constant K 4 .…”