Optical Spectrum and Magnetic Properties of Er3+ in CaWO4

Abstract

The polarized optical spectrum of ErH in calcium tungstate at 4.2 and 77°K is reported. Radial integrals and spin-orbit coupling parameter derived from fitting the position of the centers of gravity of the J manifolds in intermediate coupling are F2=423.89 em-I, F4=67.995 cm-I , F6=6.667 cm-I , 1=2377 cm-I . A first-order crystal field calculation based on the intermediate coupling states of the free ion is shown to account very satisfactorily for the optical spectrum, paramagnetic resonance, and magnetic hyperfine structure when using (r-a > and the nuclear moment measured by atomic beam triple magnetic resonance. The agreement between the experimental and calculated crystalline quantum numbers is encouraging since they were not forced to fit in the calculation. Also, the fact that the (r-a ) values obtained for a truly free erbium atom can be used for the case of the ion in a crystalline host indicates that the 41 wavefunctions are little affected by the surroundings. The values of the crystal field parameters obtained from fitting the optical spectrum are: C 2 0",,231±7 cm-I , C.4=±(852±18) cm-I , C 4 o= -90±2 cm-I , C 6 o= -0.6±0.5 cm-I , C 6 4=±(396±5) cm-I , B s -4=±(75±12) cm-I • The above parameters predict the Stark splittings of the 53 states up to 25000 cm-I with an rms deviation of 4.4 cm-I . The calculated g factors are gl (ZI) = 1.21, gJ.c(ZI) =8.45, gllc(Z2) =3.65, gJ. c (Z2) = 7.03; the corresponding measured values are 1.247, 8.38, 3.42, and6.98,respectively. The calculated and measured values of the hyperfine structure constants are: A. ale IS7 = 41.61 X 10-4 cm-I , A meas l67 = (42.5±0.5) X 10-4 cm-I , B eale I67 =290.60X 10-4 cm-I, B meas I67 = (293±3) X 10-4 cm-I •This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to

Erbium-Implanted Materials for Quantum Communication Applications

“…The peaks are all clearly resolvable, allowing the determination of all eight Z levels and all seven Y levels (Table II). The splittings reported are qualitatively similar to those known for isostructural Er 3+ -doped CaWO 4 [38].…”

“…Structure & Properties: PbWO 4 adopts the Scheelite crystal structure, in which the optical properties of doped rare-earth ions have been extensively studied [38]. Both Pb and W have isotopes with nuclear spin, 207 Pb (I= 1 2 , 22% natural abundance) and 183 W (I= 5 2 , 14% natural abundance).…”

“…CaWO 4 , which we compare PbWO 4 with below, has the same structure and similar optical properties (n o = 1.88, n e = 1.9 [33], band gap 4.2 eV). In Er 3+ -doped CaWO 4 , Er 3+ is known to occupy the Ca 2+ site, which has local S 4 symmetry [38,41].…”

“…The near perfect correspondence between the PbWO 4 and CaWO 4 spectra suggest their hyperfine constants (and thus underlying g-tensors) are extremely similar, from which we conclude that Er 3+ occupies a similar site in both cases. In CaWO 4 , Er 3+ is known to occupy the substitutional cation site [38,41].…”

“…The prominent hyperfine-split transitions are a result of the large transverse component of the hyperfine tensor [38]; this acts in the same manner as a large off-axis magnetic field, giving rise to optical transitions which flip the electron or nuclear spin. Well-resolved hyperfine transitions may find use in optical manipulation of the nuclear spin [43], potentially serving as an ancilla qubit.…”