Whispering Gallery mode ESR spectroscopy and parameters measurement in single crystal SrLaAlO4 at millikelvin temperature

Rigorous ESR spectroscopy of Fe3+ impurity ion with oxygen vacancy in ferroelectric SrTiO3 crystal at 20 mK

“…In fact this treatment is feasible for the estimation of tetragonal distortion of the octahedron, and not for in presence of iron-oxygen-vacancy (Fe 3+ − V O ) in the octahedron where Fe 3+ ion is displaced away from the oxygen vacancy V O by about 0.35 Å [35]. As a supporting results of this matter, in our ESR spectroscopy measurement of low-spin Fe 3+ trivalent ion in the SrLaAlO 4 crystal FeO 6 octahedron at 20 mK [29], the considered value of k = 0.33 is the fitted with the value η ≈ −1 according to the measured g-factor g Fe = 2.028 in the tetragonal anisotropy [21,37]. The reason is that, in case of Fe 3+ in SrLaAlO 4 , the trivalent Al 3+ ion is substituted by this trivalent Fe 3+ ion without any possibility of iron-oxygen-vacancy (Fe 3+ − V O ) in the octahedron.…”

“…High sensitivity of ESR spectr oscopy is required for such a very low concentration of impurity ions in this nearly pure SrTiO 3 crystal. Different process are devoted in measuring sensitivity of different type of resonator of wide range of frequency with varieties of probing system [24][25][26][27][28][29]. Benmessai et al [2] described a concentration level measurement process of Fe 3+ impurity ion exciting modes at millikelvin temperatures in sapphire.…”

“…Where V s is the mode volume, T s is the sample temperature, S is the electron effective spin, g e is the electron g-factor, β is the Bohr electron magneton, µ • is the magnetic permeability of free space, ω is the resonance frequency, η is the filling factor, P n is the noise power at the detector due to all sources, P is the microwave input power, and ∆ω is the width of aggregated spin frequency at resonance which is depended on the shape-function f (ω) normalized as ∞ 0 f (ω)∂ω = 1 for a wide range of Larmor precession (ω L ) of magnetic dipoles [21]. Significant output (transmission) occurs only at resonance in a very narrow frequency width ∆ω in the region ω ≈ ω L at ESR [29,31]. This frequency width is about 300 000 Hz in the ferroelectric anisotropy of the crystal SrTiO 3 crystal (see figures 1-3), and Q-factor of the selected modes were about 1000 at 20 mK temperature.…”

Ultrasensitive multi-mode ESR probed ferromagnetic two-level system of $Mn^{4+}$ impurity ion in the insulated $MnO_6$ complex of $SrLaAlO_4$ at $20~mK$

“…Measured value of P is negative as manganese nuclear electric quadruple moment is positive. Whereas, the value of P is positive for Cu 2+ ion in the same site as copper nuclear electric quadruple moment is negative 8 .…”

“…This experimental study is on impurity paramagnetic ion's unpaired electron spin states using electron spin resonance (ESR) spectroscopy in a suitable dielectric crystal resonator exciting microwave whispering gallery (WG) modes [5][6][7] . WG multi-mode ESR spectrum works as a direct probe providing information of electronic and magnetic states of paramagnetic impurity ions 8 . In this process, M n 4+ ion has been detected in the dielectric single crystal SrLaAlO 4 (SLA), and analysed taking into account an intricate electronic hybridization due to its extra charge in M nO 6 complex at 20 millikelvin (mK).…”