The physics of interacting nuclear spins in solids is well interpreted within the nuclear spin temperature concept. A common approach to cooling the nuclear spin system is adiabatic demagnetization of the initial, optically created, nuclear spin polarization. Here, the selective cooling of ⁷⁵As spins by optical pumping followed by adiabatic demagnetization in the rotating frame is realized in a nominally undoped GaAs/(Al,Ga)As quantum well. The lowest nuclear spin temperature achieved is 0.54 μK. The rotation of 6 kG strong Overhauser field at the ⁷⁵As Larmor frequency of 5.5 MHz is evidenced by the dynamic Hanle effect. Despite the presence of the quadrupole induced nuclear spin splitting, it is shown that the rotating ⁷⁵As magnetization is uniquely determined by the spin temperature of coupled spin-spin and quadrupole reservoirs. The dependence of heat capacity of these reservoirs on the external magnetic field direction with respect to crystal and structure axes is investigated.

固体中相互作用核自旋的物理学在核自旋温度概念中得到了很好的解释。冷却核自旋系统的常用方法是对初始的、光学产生的核自旋极化进行绝热退磁。在这里，通过光泵浦选择性冷却⁷⁵ As 自旋，然后在旋转框架中进行绝热退磁，是在名义上未掺杂的 GaAs/(Al,Ga)As 量子阱中实现的。实现的最低核自旋温度为 0.54 μ K。动态 Hanle 效应证明了6 kG 强 Overhauser 场在5.5 MHz的⁷⁵ As Larmor 频率下的旋转。尽管存在四极诱导核自旋分裂，但表明旋转的⁷⁵由于磁化强度由耦合自旋-自旋和四极子储层的自旋温度唯一确定。研究了这些储层的热容量对相对于晶轴和结构轴的外部磁场方向的依赖性。