Spin–Lattice Relaxation and Cross-Relaxation Interactions in Chromium Corundum

Reversible Modulation of the Cr3+ Spin Dynamics in Colloidal SrTiO3 Nanocrystals

“…27,28 Prokhorov first demonstrated that the spin−lattice relaxation times of (Al 1−x M x ) 2 O 3 differ by many orders of magnitude at cryogenic temperatures for M = Cr 3+ or Ti 3+ . Spin−lattice relaxation times at 4.2 K for Cr:Al 2 O 3 are ∼50 ms, whereas for Ti:Al 2 O 3 T 1 = ∼0.1 ms. 27 These reported times are also sensitive to temperature and dopant concentration (self-or resonant crossrelaxation). 28 Here, the difference in P 2 between Cr 3+ in Cr:SrTiO 3 NCs and Ti 3+ in photodoped SrTiO 3 NCs is much smaller than in Al 2 O 3 .…”

“…32 Using eq 1b and the experimental P 2 value, T 1 ≈ 150 μs. A strong concentration dependence results in a range of T 1 values between 170 μs and 110 ms for Cr 3+ in bulk Al 2 O 3 at 4.2 K. 32,33 A similar study of the concentration dependence of T 1 has not been performed for Cr 3+ in bulk SrTiO 3 , but for a Cr concentration of 0.05%, the value at 4.2 K is T 1 ≈ 1−5 ms. 34 The faster spin−lattice relaxation of the Cr 3+ dopants in SrTiO 3 NCs before photodoping could arise from heterogeneity in dopant location and proximity to NC surfaces. 35 Unfortunately, accurate deconvolution of the line widths for the photodoped Cr:SrTiO 3 samples was complicated because of the overlapping signals of Cr 3+ and Ti 3+ .…”

Thermally-Polarized Solid-State Spin Sensor

“…The fit was carried out at 0 dBm, which is the lowest power at which an accurate fit is possible. The resulting T 1 and T 2 parameters are compared against results from [90] and shown in Table III, demonstrating reasonable agreement.…”

“…However, the fit for κ th is sensitive to the fitting method and applied MW power. Specifically, fitting becomes very poor at lower applied MW powers (compared to T 1 values in [90]). This behavior can be understood by looking at the reflection coefficient Γ, which depends on κ th through the interaction term Π given in Eq.…”

“…must therefore be on the same order or greater than κ s /2 = 1/T 2 . Using the literature values T 1 = 2.6 µs and T 2 = 5.5 ns [90] and solving κ s /2 = g 2 s ncav κ th results in an applied MW power of 2 dBm. Thus, the fit found by applying 0 dBm of power should be able to estimate κ th , but any lower powers would become increasingly unreliable.…”