Bøger af Thomas Joe

Nd-based manganites are a class of materials that have been extensively studied due to their interesting magnetic and electrical properties. They belong to the family of mixed-valent manganites, which are characterized by the presence of Mn ions with different valence states.One of the most fascinating features of Nd-based manganites is their colossal magnetoresistance (CMR), which is the ability of the material to undergo a significant change in resistance when subjected to a magnetic field. This effect is due to the competition between the ferromagnetic and the antiferromagnetic interactions between the Mn ions. When the magnetic field is applied, it aligns the magnetic moments of the Mn ions, leading to a decrease in the resistance of the material. This effect has significant technological implications and has led to the development of new devices, such as magnetic sensors and magnetic memory.The magnetic properties of Nd-based manganites are also closely related to their electrical transport behavior. In these materials, the charge carriers are mainly the electrons, which move through the material in response to an electric field. The interaction between the charge carriers and the Mn ions is responsible for the electronic transport properties of the material, which can range from metallic to insulating depending on the temperature, magnetic field, and doping level.The structural properties of Nd-based manganites are also critical in determining their magnetic and electrical properties. These materials crystallize in a perovskite structure, which consists of corner-sharing octahedra of oxygen atoms. The distortion of the octahedral structure due to the presence of the Mn ions with different valence states leads to the formation of charge and spin ordering, which affects the electronic transport properties.In recent years, there has been a growing interest in the study of the multiferroic properties of Nd-based manganites, which refers to the coupling between the magnetic and electric properties of the material. This coupling can be achieved through the application of an external magnetic field or by controlling the temperature and doping level of the material. The multiferroic properties of Nd-based manganites have potential applications in the development of new devices, such as magnetic-field-controlled switches and sensors.In conclusion, Nd-based manganites are a fascinating class of materials that exhibit a range of interesting magnetic and electrical properties. These properties are closely related to the material's structural properties and can be controlled by external factors such as temperature, doping level, and magnetic field. The study of these materials has significant implications for both fundamental research and technological applications, and it is likely that new discoveries will continue to emerge in this field in the future.