Measurements of magnetic susceptibilities and anisotropy of erbium pyrogermanate (Er2Ge2O7) crystal

Local-Ising-type magnetic order and metamagnetism in the rare-earth pyrogermanate Er2Ge2O7

“…To temperature of θ w = −14.4(2)K. We find a negative Weiss temperature indicating antiferromagnetic (AFM) order in agreement with Ghosh et al 31 . However, the absolute value of our Weiss temperature is larger than previously reported, we attribute this to the finer temperature steps and higher temperature cutoff (120 K) used in our analysis the former of which allows for the range of linear behavior to be more carefully determined 31 .…”

“…We observe no evidence of magnetic ordering down to 2 K. Above ∼ 100 K typical Curie-Weiss behavior is seen as reported for both Ho 2 Ge 2 O 7 and Dy 2 Ge 2 O 7 . Fitting the inverse susceptibility by the Curie-Wiess law (χ −1 = C(T −θ w )) we obtain an effective magnetic moment of µ ef f = 9.8(3)µ B /Er and a Weiss temperature of θ w = −14.4(2)K. We find a negative Weiss temperature indicating antiferromagnetic (AFM) order in agreement with Ghosh et al 31 . However, the absolute value of our Weiss temperature is larger than previously reported, we attribute this to the finer temperature steps and higher temperature cutoff (120 K) used in our analysis the former of which allows for the range of linear behavior to be more carefully determined 31 .…”

“…Furthermore, the magnetic ordering temperature follows a similar trend, decreasing with decreasing moment size from 2.2 to 1.6 to 1.15 K. Although the crystallographic parameters of the Dy compound are not reported, the decrease in T N correlates with the lattice contraction anticipated for the reduction in ionic radius from Dy to Ho to Er 41 . Interestingly, the θ w follows the opposite trend reaching a maximum absolute value of 14.4 K for the Er compound and decreasing to 9.6 and 4.4 K for Ho and Dy respectively [29][30][31] . Considering the complex dynamic magnetic behavior reported in both Ho 2 Ge 2 O 7 and Dy 2 Ge 2 O 7 which indicated multiple competing interactions and time-scales, it is unsurprising that simple moment size considerations are inadequate here for predicting the bulk magnetic behavior which is likely tuned by subtle effects in the ErO 7 local environment and the corresponding crystal field levels.…”

“…Despite this potential, little work has been performed on the REPG family. Beyond the intial synthesis report, only the Ho 2 Ge 2 O 7 , Dy 2 Ge 2 O 7 and Er 2 Ge 2 O 7 members of the REPG family have recieved further study [29][30][31] . These members crystallize with the tetragonal space group P 4 1 2 1 2 and exhibit highly anisotropic magnetic susceptibilities.…”

Structure and magnetic properties of theHo2Ge2O7pyrogermanate

“…The coordination polyhedron of the rare earth is a distorted pentagonal bipyramid [1][2] with its axis almost parallel to the crystallographic c direction. The optical properties [3][4] and magnetic susceptibility of the R 2 Ge 2 O 7 compounds [3,[5][6][7][8] have often been interpreted in light of the four equivalent magnetic sites per unit cell and their local 5-fold symmetry, though the findings of a Mossbauer study on Er 2 Ge 2 O 7 [9] indicate that the pentagonal crystal field model around the R atoms is invalid at least in that case.…”