The nanocomposite magnet based on the exchange coupling effect is a candidate for the new generation of permanent magnets. While the mismatch between the soft and hard magnetic phases introduces a remanence (M_r)–coercivity (H_C) trade-off, it prevents a high performance. Here, a gradient multiphase (GMP) heterogeneous structure was constructed to break the M_r–H_C trade-off in nanocomposite magnets. GMP Sm-Co/FeCo magnet, which comprises multiple Sm-Co hard magnetic phases (1:3, 2:7, 1:5, 1:7, and 2:17) and FeCo soft magnetic phase, achieves both a high H_C (6.4 kOe) and a high M_r (119 emu/g), yielding a remanent–saturation magnetization ratio (M_r/M_S) of 0.87 and high energy product ((BH)_max) of 25.7 MGOe. In situ magnetic domain observations and micromagnetic simulations revealed that the pinning of multiple hard magnetic phases in the GMP structure forms quasi-magnetic domains composed of multiple magnetic phases. The hard magnetic phases at the edges of the quasi-domains form pinning sites, which provide full pinning action and impede the expansion of the demagnetized domains centered on the soft magnetic phases, leading to superior performance. Further micromagnetic simulations verified that the exchange coupling in GMP Sm-Co/FeCo magnets is improved compared to biphasic (BP) nanocomposite magnets. The strategy of GMP structure can be applied to circumvent performance trade-offs in other heterogeneous functional materials.

Barocaloric effect underlies a promising emission-free and highly efficient cooling technology. The current wisdom to design barocaloric materials is to find materials undergoing a temperature-induced phase transition with huge latent heats and then to apply a pressure to harvest the heat. So far, the entropy change of the temperature-induced phase transition usually sets the upper limit for the barocaloric effect. Here we proposed and realized a large barocaloric effect at approaching a triple-phase point in odd-numbered n-alkanes. A low pressure can drive the phase transition from the liquid state to the disordered solid state and the phase transition from the disordered solid state to the ordered solid state to be merged at 297 K. These phase transition behaviors are well explained by in-situ Raman scattering and complementary molecular dynamics simulations. Around such a point, an adiabatic temperature change as large as ~30 K has been achieved under 150 MPa. The high coefficient of phase transition temperature with respect to pressure makes the triple-phase-point temperature to be continuously tuned by pressure and a wide refrigeration temperature window of more than 50 K (280–335 K) was realized. The strategy could initiate a new research avenue and shed light on designing novel high-performance barocaloric materials.