Low-Frequency Optically Detected EPR of Sm 3+ in Cs 2 NaYF 6 Single Crystal M. L. Falin • K. I. Gerasimov • N. M. Khaidukov Received: 26 July 2010 / Revised: 23 September 2010 / Published online: 17 October 2010 Ó Springer-Verlag 2010 Abstract The Sm 3? ion in the Cs 2 NaYF 6 single crystal was studied by optically detected electron paramagnetic resonance spectroscopy. Magnetic resonance signals were recorded by Faraday rotation at the frequency of 0.6–0.85 GHz and magnetic fields of about 0.14 T. The hyperfine parameters of 147 Sm 3? and 149 Sm 3? isotopes were determined. 1 Introduction Fluoroelpasolites M 2 ABF 6 (M ? ,A ? ,B 3? are univalent and trivalent metal cations), with the cubic structure (Fig. 1) in a wide temperature interval are perfect model systems in which the isomorphous substitution of trivalent rare-earth (RE) ions for B 3? cations provides an opportunity to study optical and magnetic properties of dopants in a wide concentration range. In turn, it allows one to consider these compounds as promising materials in practice. Although elpasolite-type crystals doped with RE ions and native lanthanide elpasolites M 2 ALnX 6 (X - is a halogen anion) have been studied extensively by electron paramagnetic resonance (EPR), optical and Raman spectroscopy [1–12], but the crystal field parameters and EPR data for the Sm 3? ion in Cs 2 NaYF 6 are absent. The ground multiplet of Sm 3? is 6 H 5/2 , which is split by a cubic crystal field into a quartet C 8 and a doublet C 7 . In the octahedral coordination, the latter is the lowest level. The low value of the g-factor of this state is one of the reasons why the M. L. Falin (&)  K. I. Gerasimov Zavoisky Physical-Technical Institute, Russian Academy of Sciences, 420029 Kazan, Russian Federation e-mail: falin@kfti.knc.ru N. M. Khaidukov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 117907 Moscow, Russian Federation 123 Appl Magn Reson (2011) 40:31–35 DOI 10.1007/s00723-010-0175-3 Applied Magnetic Resonance