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Polycrystalline Zn1-x(Mn:Ni)x0 sample for x = 0.02 were synthesized by solid state route. We have observed low field microwave absorption in these powder samples. Low field microwave absorption signal is out of phase with the regular resonance signal indicating the microwave absorption has a minimum at zero field and the absorption of microwaves increases with increase of magnetic field. Low field microwave absorption in these powders is qualitatively different from their bulk pellets. Temperature dependence of the low field microwave absorption indicates a line shape evolution and a non-monotonic peak to peak intensity change. Further, we have observed the absence of 2nd harmonic in this low field microwave absorption, indicating low field microwave absorption in these transition metal co-doped ZnO powders is not non-linear in nature. [ABSTRACT FROM AUTHOR]

Tunability of key length scales including nanodimensionality, mean free path, localization length, and cyclotron radius gives opportunities to fabricate nanodevices with new functionalities. Herein, in order to tune localization length, composite nanorods (CNRs) of 2-naphthalene sulfonic acid doped polyaniline (PANI-NSA) and nickel ferrite nanoparticles (NiFe2O4 NPs) are synthesized via an in situ chemical polymerization method. The nanorods' structure and the incorporation of the NiFe2O4 NPs into the PANI-NSA matrix are envisaged by various characterization techniques. The presence of a hysteresis loop with minor coercivity and remanence suggests the ferrimagnetic property of PANI-NSA/NiFe2O4 CNRs at room temperature. Investigation of electrical resistivity as a function of temperature in the absence of an external magnetic field establishes quasi-one-dimensional variable range hopping conduction mechanism of the PANI-NSA/NiFe2O4 CNR samples. CNR samples with two different loadings of NiFe2O4 NPs demonstrate substantial amounts of magnetoresistance (MR) at all the temperatures (300–50 K) studied. Intriguingly, a transition from positive to negative MR is observed with an increase in temperature from 200 to 300 K for CNR samples with less amount of NiFe2O4 (CNRs 1), whereas MR is positive for CNRs with higher loading of NiFe2O4, throughout the studied temperatures. Positive and negative MR behaviors of the CNR samples are quantitatively elucidated in terms of wave function shrinkage and forward interference models. Deduced localization length from the forward interference regime for CNRs 1 is about one order of magnitude larger than that in the wave function shrinkage regime. Thus, tuning of localization length can be achieved qualitatively through appropriate loading of NiFe2O4 NPs. [ABSTRACT FROM AUTHOR]

Electronic devices made of organic materials are critical for sustainable technology and the reduction of electronic waste. In this paper, we report on the resistive switching (RS) behavior of an organic full cream cow milk-based film placed between two electrodes. The switching properties of the milk film were investigated for use in RS memory (ReRAM), a new type of memory device. Two devices were created: one with electrodes made of silver (Ag) and indium doped tin oxide (ITO) (Ag/cow milk/ITO) and the other with electrodes made of Ag and tungsten (W) (Ag/cow milk/W). The study is unique in two ways: (1) the use of the spin coat method, which allowed us to deposit 15 nm thin milk films, and (2) the use of ITO and W bottom electrodes, which allowed us to compare the results. Our findings show that both ITO- and W-based devices exhibit RS properties with "S-type" bipolar behavior. The ITO-based device exhibited switching at 0.77 V and an ION/IOFF ratio of ∼ 2. The memory behavior of this device lasted ∼7 write/erase cycles, indicating the possibility of nonvolatile memory application. In contrast, the switching in the W-based device was characterized by low (0.1 V) voltage, and it lasted for only one cycle. Increasing the compliance current to 0.5 A improved the ON/OFF ratio to 102, but the device could not repeat the same hysteresis behavior. The analysis of the conduction and switching mechanisms in both devices revealed a conductive bridge mechanism attributed to the metalization of metal ions naturally found in milk. Overall, our findings show that the thickness of the milk film influences both conduction and switching mechanisms and that the (milk film)/ITO and (milk film)/W interfaces influence the conductance of full cream cow milk-based ReRAM devices. [ABSTRACT FROM AUTHOR]

We studied the low-field microwave absorption (LFMA) in polycrystalline pellet and powdered (0.1–0.2 µm particle size) samples with a nominal composition of Zn1 − x(Mn:Fe(Ni))xO (x = 0.02). LFMA signals are stronger in the case of Mn:Fe co-doped ZnO, as compared to that of Mn:Ni co-doped ZnO. While the bulk samples show hysteresis, it disappears in the case of powdered samples. Further the line shapes of LFMA were modified with powdering, leading to small saturation fields for LFMA. This indicates that the microwave absorption in these powders is more sensitive than in the pellet form. We interpret these results in terms of interparticle–interfacial pinning. In this work, we clearly establish the low-field tunability of microwave absorption in the Zn1 − x(Mn:Fe(Ni))xO (x = 0.02) system, which is good for the applications as microwave absorbers with small field tunability as a functionality. This means LFMA can give inputs for the right choice of material for field-tunable microwave absorber design. [ABSTRACT FROM AUTHOR]