Physics – Condensed Matter – Materials Science
Scientific paper
2007-12-18
Physics
Condensed Matter
Materials Science
24 pages, 6 figures, Accepted for publication in Phys. Rev. B
Scientific paper
10.1103/PhysRevB.77.054408
We present here magnetization, specific heat and Raman studies on single-crystalline specimens of the first pyrochlore member $Sm_2Ti_2O_7$ of the rare-earth titanate series. Its analogous compound $Sm_2Zr_2O_7$ in the rare-earth zirconate series is also investigated in the polycrystalline form. The Sm spins in $Sm_2Ti_2O_7$ remain unordered down to at least T = 0.5 K. The absence of magnetic ordering is attributed to very small values of exchange ($\theta_{cw} ~ -0.26 K$) and dipolar interaction ($\mu_{eff} ~ 0.15 \mu_B$) between the $Sm^{3+}$ spins in this pyrochlore. In contrast, the pyrochlore $Sm_2Zr_2O_7$ is characterized by a relatively large value of Sm-Sm spin exchange ($\theta_{cw} ~ - 10 K$); however, long-range ordering of the $Sm^{3+}$ spins is not established at least down to T = 0.67 K, due to frustration of the $Sm^{3+}$ spins on the pyrochlore lattice. The ground state of $Sm^{3+}$ ions in both pyrochlores is a well-isolated Kramer's doublet. The higher-lying crystal field excitations are observed in the low-frequency region of the Raman spectra of the two compounds recorded at T = 10 K. At higher temperatures, the magnetic susceptibility of $Sm_2Ti_2O_7$ shows a broad maximum at T = 140 K while that of $Sm_2Zr_2O_7$ changes monotonically. Whereas $Sm_2Ti_2O_7$ is a promising candidate for investigating spin-fluctuations on a frustrated lattice as indicated by our data, the properties of $Sm_2Zr_2O_7$ seem to conform to a conventional scenario where geometrical frustration of the spin exclude their long-range ordering.
Dhar Sudesh Kumar
Revcolevschi Alexandre
Saha Surajit
Singh Surjeet
Sood Ajay K.
No associations
LandOfFree
Manifestation of geometric frustration on magnetic and thermodynamic properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Manifestation of geometric frustration on magnetic and thermodynamic properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manifestation of geometric frustration on magnetic and thermodynamic properties of pyrochlores $Sm_2X_2O_7$ (X=Ti, Zr) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-145858