For the first time the magnetocaloric properties of La0.9Ag0.1MnO3, La0.8Ag0.2MnO3, La0.85Ag0.15MnO3, La0.8Ag0.15MnO3 and La0.8Ag0.1MnO3 manganites have been investigated by direct and indirect measurement techniques. All samples showed almost the same relative cooling power (RCP). Temperatures of maxima of the magnetocaloric effect (MCE) are between a few degrees below freezing and the room temperature region. The compounds showed RCP values of about 100 J kg−1 at a field change of 2.6 T, which is about half the RCP of gadolinium. Because of considerable MCE and the Curie temperatures ranging from 269 to 303 K, these materials could be used as magnetic refrigerants for magnetic refrigeration in the sub-room and room temperature range.

We report on measurements of anisotropic magnetoresistance (AMR) (∼ρ‖−ρ⊥) along two orthogonal directions ([001] and [1−10]) of a manganite (La0.95Ag0.05MnO3) epitaxial thin film grown on a (011) SrTiO3 substrate. We show that AMR along [001] is negative whereas along the [1−10] direction is positive at low temperature, changing to negative when approaching the Curie temperature. We argue that temperature dependent anisotropic spin-orbit coupling and spin-dependent scattering effects could be at the basis of these experimental results.

The purpose of this study was to introduce newly synthesized nanomaterials as an alternative to superparamagnetic ironoxide based particles (SPIO) and thus to launch a new platform for highly controllable hyperthermia cancer therapy and imaging. The new material that forms the basis for this article is lanthanum manganite particles with silver ions inserted into the perovskite lattice: La(1-x)Ag(x)MnO(3+delta). Adjusting the silver doping level, it is possible to control the Curie temperature (T(c)) in the hyperthermia range of interest (41-44 degrees C). A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) is suggested. New nanoparticles are stable, and their properties were not affected by the typical ambient conditions in the living tissue. It is possible to monitor the particle uptake and retention by MRI. When these particles are placed into an alternating magnetic field, their temperature increases to the definite value near T(c) and then remains constant if the magnetic field is maintained. During the hyperthermia procedure, the temperature can be restricted, thereby preventing the necrosis of normal tissue. A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) was suggested. Ag-doped perovskite manganites particles clearly demonstrated the effect of adjustable Curie temperature necessary for highly controllable cellular hyperthermia. The magnetic relaxation properties of the particles are comparable with that of SPIO, and so we were able to monitor the particle movement and retention by MRI. Thus, the new material combines the MRI contrast enhancement capability with targeted hyperthermia treatment.

No abstract

A comprehensive investigation of the electro- and thermophysical properties of the manganite La0.8Ag0.15MnO3 is carried out over a wide temperature interval (4.2–350K) and in magnetic fields up to 26kOe. It is shown that the colossal magnetoresistance in a magnetic field of 11kOe amounts to 57%, and the effect is maximum at room temperature. The dominant mechanisms of current carrier scattering in the ferromagnetic and paramagnetic phases are established. An analysis of the data on the low-temperature heat capacity provides estimates of the electronic density of states at the Fermi level, NF=6.82×1024eV−1mol−1, and of the Debye temperature, θD=370K. The results of thermal expansion measurements are used to find the spontaneous magnetostriction. It is found that the phonon mechanism of heat transfer is dominant, and the local Jahn–Teller distortions are considered as the main mechanism of phonon scattering.