Figure 8

Adiabatic demagnetization of the mutual interactions. Main panel: entropy as a function of temperature for \(B=0\) T (solid cyan curve) and for ΔB_loc = 0.0032 T (red dashed line). The yellow gradient indicates the region of relevance of B_loc in the regime of ultra-low temperatures. Inset: schematic representation of the adiabatic magnetization employing the mutual interactions. The steps are as follows: i) the system is cooled down to a sufficiently low temperature where the magnetic energy associated with B_loc overcomes the thermal fluctuations (path A to B); ii) the temperature is adiabatically increased from B (T₁) to C (T₂) and, in order to hold the entropy constant, the system is magnetized adiabatically, i.e., a finite value of ΔB_loc emerges into the system and thus, the entropy changes from the solid cyan to the fictitious red dashed line, which emulates S versus T for the corresponding value of (B_loc + ΔB_loc); iii) upon increasing the temperature from C, the entropy will vary and, as a consequence, the system will be demagnetized at T = 4.35 mK (indicated by the solid black arrow), going back to its original configuration of ΔB_loc = 0 T. Such process can be restarted by cooling the system again from T = 4.35 mK to point A. Figure created with use of OriginPro (version 2020)⁶³ and Wolfram Mathematica (version 11)⁶⁴.