As electronic technology continues to evolve towards miniaturization and integration, the demand for micro-refrigeration technology in microelectronic systems is increasing. Ferroelectric (FE) refrigeration technology based on the electrocaloric effect (ECE) has emerged as a highly promising candidate in this field, due to its advantages of high energy efficiency, simple structure, easy miniaturization, low cost, and environmental friendliness. The EC performance of FE materials essentially depends on the phase transition features under the coupled electric and thermal fields, making the $E$-$T$ phase diagram a core tool for decoding the underlying mechanism of ECE. This paper reviews the development of EC materials, focusing on the comprehensive study of $E$-$T$ phase diagrams. By correlating the microscopic phase structure of FE materials with the macroscopic physical properties, it clarifies the manipulation mechanism for enhanced ECE performance, providing theoretical support for the targeted design of high-performance EC materials. In the future, the introduction of data-driven methods is expected to enable the high-throughput construction of FE phase diagrams, thereby accelerating the optimization of high-performance EC materials and promoting the practical application of FE refrigeration technology.

The electrocaloric (EC) effect refers to the change in the polarization entropy and/or temperature of dielectric materials when an electric field is applied and removed. EC refrigeration has received increasing interest as an alternative to conventional refrigeration technologies because it provides both high energy efficiency and zero global warming potential. In this review, we first introduce the thermodynamic fundamentals of the EC effect and the mechanism of EC refrigeration cycles. We then present recent advances in EC cooling technologies, from material improvements to device demonstrations, including a critical analysis of existing material and device characterization methodologies and a discussion of how to reliably measure the parameters of materials and devices. Finally, the current challenges and possible future prospects for EC cooling technology are outlined.

Thermomagnetic generation (TMG), a heat-to-electricity conversion technology based on the thermomagnetic effect, offers high reliability and broad adaptability to diverse heat sources. By exploiting the temperature-dependent magnetization of thermomagnetic materials, TMG converts thermal energy into electrical energy through cyclic changes in magnetic flux based on Faraday's law. The performance of TMG systems is largely governed by the intrinsic properties of the working materials and the design of device architecture. Ideal TMG materials exhibit sharp and reversible magnetization transitions near the operating temperature, low thermal hysteresis, and high thermal conductivity. Device configurations can be broadly categorized into active and passive systems: active TMG devices rely on controlled thermal cycling and optimized magnetic circuits for enhanced output, whereas passive devices utilize self-actuated mechanical motion to generate electricity. In this topical review, we provide a comprehensive overview of recent advances in TMG materials and device configurations. Furthermore, we discuss future development trends and offer perspectives on experimental strategies to advance this field.

Accessing the milli-Kelvin regime is increasingly important for next-generation quantum technologies and deep-space observations. Among established cryogenic techniques, adiabatic demagnetization refrigeration (ADR) is distinctive for its all-solid-state design, low vibration, and intrinsic gravity independence. Here we present a materials-centered review of ADR refrigerants, connecting classical thermodynamics to modern quantum many-body behavior. Beyond hydrated paramagnetic salts, dense rare-earth oxides and correlated-disorder ceramics, we highlight emerging quantum-engineered refrigerants, including geometrically frustrated magnets, and quantum-critical systems. In these materials, suppressing long-range order and tailoring low-energy excitations redistribute spin entropy into the sub-Kelvin window, enabling large and reversible entropy changes at the lowest accessible temperatures. We discuss the central trade-offs among volumetric entropy density, thermal transport, and magnetic ordering, and outline possible design rules for staged ADR architectures.

Topology, as a mathematical concept, has been introduced into condensed matter physics since the discovery of quantum Hall effect, which characterizes new physical scenario beyond the Landau theory. The topologically protected physical quantities, such as the dissipationless quantum transport of edge/surface states as well as magnetic/dipole quasi-particles like skyrmions/bimerons, have attracted great research enthusiasms in the past decades. In recent years, another kind of topology in condensed matter was revealed in the magnetoelectric parameter space of multiferroics, which deepens our understanding of magnetoelectric physics. This topical review summarizes recent advances in this area, involving three types of type-II multiferroics. With magnetism-induced ferroelectricity, topological behaviors can be manifested during the magnetoelectric switching processes driven by magnetic/electric fields, such as Roman-surface/Riemann-surface magnetoelectricity and magnetic crankshaft. These exotic topological magnetoelectric behaviors may be helpful to pursue energy-efficient and precise-control devices for spintronics and quantum computing.