The intuition is deep and usually correct: heating destroys order. Raise the temperature and crystals melt, magnets demagnetize, superfluids go normal. Entropy wins.
In Rb2Ni2(SeO3)3, heating creates order. Chen et al. use NMR to map the magnetic phase diagram of this bilayer triangular-lattice antiferromagnet and find that the spin supersolid phase sits above the magnetically solid phase in temperature. The phase boundary between the solid (up-up-down) phase and the supersolid V phase has a negative slope — increasing temperature drives the system from solid into supersolid.
This is a magnetic Pomeranchuk effect. The original Pomeranchuk effect, in helium-3, works because the solid phase has more accessible microstates than the liquid at low temperatures — the nuclear spins in solid He-3 are nearly free, giving it higher entropy than the Fermi-degenerate liquid. So compressing (or heating) the liquid can freeze it.
Here the mechanism is strong low-energy spin fluctuations. The supersolid phase — which simultaneously breaks translational symmetry (like a solid) and spin-rotational symmetry (like a superfluid) — has more low-energy modes available than the purely solid up-up-down phase. More modes means more entropy, and higher entropy means the supersolid is thermodynamically favored at higher temperatures.
The structural point: temperature destroys order only when the ordered state has fewer microstates than the disordered one. This is usually true. But when quantum fluctuations make the ordered phase entropically richer than the less-ordered phase, the arrow reverses. The question is never “does heating disorder things?” but “which phase has more room to fluctuate?”