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Partial replacement of La by Bi in La0.67Ca0.33MnO3 depresses the ferromagnetic order of the compound and leads to a stepwise magnetic behavior characterized by two subsequent transitions at ~ 120 K and ~ 225 K. Based on a combined study of the electron spin resonance spectra and the thermal and isothermal magnetization, a complete scenario for the phase separation that causes the complex behavior has been given. It is found that the paramagnetic phase exists in a wide temperature region even below the ferromagnetic onset at ~ 225 K. It coexists with the ferromagnetic phase below ~ 240 K and with both the ferromagnetic and antiferromagnetic phases below ~ 190 K with a reduced but significant fraction. The magnetization jump at ~ 120 K is possibly a conversion of the remaining paramagnetic phase into the ferromagnetic phase.

Postoperative recurrence and metastasis are the major problems for the current treatment of hepatocellular carcinomas (HCC) in the clinic, including hepatectomy and liver transplantation. Here, we report that arsentic-loaded nanoparticles (ALNPs) are able to reduce the invasion of HCC cells in vitro, and, more importantly, can strongly suppress the invasion and metastasis of HCC in vivo without adverse side effects. Compared to free drug arsenic trioxide , ALNPs can deliver the drug into cancer cells more efficiently, destroy the structure of microtubules and reduce the aggregation of microfilaments in cell membranes more significantly. Furthermore, our results also reveal that tumor cells in murine blood were reduced remarkably after intravenous injection of ALNPs, indicating that this nano-drug may efficiently kill circulating tumor cells in vivo. In conclusion, our nano-drug ALNPs have great potential for the suppression of metastasis of HCC, which may open up a new avenue for the effective treatment of HCC without metastasis and recurrence.

The effects of series resistance in heterojunctions composed of La0.5Ca0.5MnO3 (LCMO) and Nb:SrTiO3 with 0.05 wt.% and 0.7 wt.% of Nb doping (0.05NbSTO and 0.7NbSTO) have been investigated in detail using current–voltage curves with and without light illumination. Two linear plots, namely, dV/dlnJ versus J and H(J)[≡V-(nk B T/q)ln(J/A**T 2)] versus J, have been used to extract the series resistance. These two plots give very close values. The extracted series resistance exhibits a monotonous increase with decreasing temperatures, which could explain the observed anomalous temperature dependence of short circuit current in LCMO/0.7NbSTO.

We have studied the electrically tunable strain effects on phase-separated Pr0.5Sr0.5MnO3 films epitaxially grown on ferroelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (001) substrates. Upon cooling, the film shows a ferromagnetic metal to antiferromagnetic insulator (FMM-AFI) transition at low temperature. Such a transition is depressed and finally disappears in electrical properties with increasing electric field applied on the substrate. Under an electric field of 6?kV/cm, a large reversible resistance drop (?85%) as well as an enhancement of magnetization is achieved. In situ X-ray diffraction indicates that the substrate-induced strain plays a crucial role in determining the properties in the film by tuning the phase competition between the ferromagnetic metallic and antiferromagnetic insulating state. The FMM-AFI transition in the film is demonstrated to be originated from a large biaxial strain. With decreasing strain, the FMM state is enhanced, leading to a colossal elastoresistance.

Epitaxial La0.8Ca0.2MnO3 (LCMO) thin films with varied thicknesses were successfully grown on 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) substrates with pulsed-laser deposition. Due to a large lattice mismatch between LCMO and PMN-PT, in-plane tensile strain was introduced into the LCMO layers. The tensile strain could be controlled by varying the layer thickness of LCMO. It was found that the in-plane tensile strain in LCMO layers could enhance the electroresistance (ER) effect significantly. A maximum value of ER ((R10??A?R1?mA)/R10??A?100%) was found to be ~80% in a 10?nm thick LCMO film that suffered a 2.21% in-plane tensile strain. The mechanism for the impact of strain on the ER effect is discussed within the framework of the electron-lattice coupling and the phase separation scenario.

We have deposited La0.8Ca0.2MnO3 (LCMO) thin films onto a 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single-crystal substrate to construct field effect devices and investigated the electric-field–induced strain and polarization effects on the structure, magnetic, and transport properties of LCMO films. LCMO not only exhibits the usual insulator-metal transition associated with the onset of ferromagnetic state, but also a lower-temperature metal-insulator transition due to charge/orbital order. Especially, the latter transition can be modulated reversely and continuously by electric fields, leading to a large electroresistance in LCMO films (ΔR/R(0) of ~70% at 50 K). Such phenomenon could be explained based on the coactions of the piezoelectric effect and the ferroelectric-field polarization effect, which could ultimately tailor the strain and density of charge carriers in LCMO films.

We had epitaxially grown La0.9Sr0.1MnO3 (LSMO) thin films on ferroelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-PT) single-crystal substrates. The electric-field controls of transport and photoinduced resistance (PR) changes were observed in LSMO films. The variations of PR under different electric fields applied to the LSMO/PMN-PT structure were quite different when PMN-PT was in positively and negatively polarized states, which can be attributed to the coaction of both electric-field–induced lattice strain effect and ferroelectric polarization effect. These results provide us another route to see the nature of modulating the properties of manganite films by external electric fields.

Manganite/ferroelectrics heterostructures were formed by growing a La0.8Ca0.2MnO3 film on single crystal of ferroelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-PT). In such heterostructures, the lattice strain can be well controlled by the electric field applied to PMN-PT. Thus the properties of the La0.8Ca0.2MnO3 layer become tunable. Significant modulations on both insulator-metal (I-M) phase transition and resistivity (~15%) were achieved under a field of 8 kV/cm. The compression of the manganite lattice in the (a,b)-plane resulted in a lower resistance and higher I-M transition temperature, demonstrating an enhanced ferromagnetic-metallic phase. Such a modulation of competing phases was ascribed to the distortion of the MnO6 octahedron.

Well and poorly crystallized iron oxide nanoshells (or hollow nanoparticles) were successfully fabricated using the Kirkendall effect in an oxygen and in an air environment using Fe nanoparticles. The low-field, zero-field–cooling (ZFC) and field-cooling (FC), measurements on these two samples indicated that the inter-particle interactions between the well-crystallized nanoshells were much stronger than those in the poorly crystallized nanoshell assembly. However, the memory experiments showed that there was no spin-glass phase in the well-crystallized nanoshell assembly, whereas the signature of the spin-glass phase (or the memory effect) was evident in the poorly crystallized nanoshell assembly. This result suggests that the origin of the spin-glass characteristic observed in the poorly crystallized nanoshells is the existence of the spin-glass phase within those particular nanoshells.