The origin and influence of finite size effects on the nonlinear dynamics of space charge stored by multi-layer graphene on ferroelectric and resistivity of graphene channel were analyzed. Here, we develop a self-consistent approach combining the solution of electrostatic problems with the nonlinear Landau-Khalatnikov equations for ferroelectric. The size-dependent behaviors are governed by the relations between the thicknesses of multi-layer graphene, ferroelectric film and the dielectric layer.The appearance of charge and electro-resistance hysteresis loops and their versatility stem from the interplay of polarization reversal dynamics and its incomplete screening in an alternating electric field.These features are mostly determined by the dielectric layer thickness. The derived analytical expressions for electric fields and space charge density distribution in a multi-layer system enable knowledge-driven design of graphene-on-ferroelectric heterostructures with advanced performances.We further investigate the effects of spatially non-uniform ferroelectric domain structures on the graphene layers conductivity and predict its dramatic increase under the transition from multi-to single-domain state in ferroelectric. This intriguing effect can open new possibilities for the graphenebased sensors and explore the physical mechanisms underlying in the operation of graphene field effect transistor with ferroelectric gating.

We consider a typical heterostructure "domain patterned ferroelectric film − ultra-thin dielectric layer − semiconductor", where the semiconductor can be an electrolyte, paraelectric or multi-layered graphene.Unexpectedly we have found that the space charge modulation profile and amplitude in the semiconductor, that screens the spontaneous polarization of a 180-degree domain structure of ferroelectric, depends on the domain structure period, dielectric layer thickness and semiconductor screening radius in a rather non-trivial nonlinear way. Multiple size effects appearance and manifestation are defined by the relationship between these three parameters. In addition, we show that the concept of effective gap can be introduced in a simple way only for a single-domain limit. Obtained analytical results open the way for understanding of current-AFM maps of contaminated ferroelectric surfaces in ambient atmosphere as well as explore the possibilities of conductivity control in ultra-thin semiconductor layers.

Tailoring of ferroelectric properties of copolymer P(VDF-TrFE) by incorporation of ceramic inclusions in the polymer matrix is promising for advanced applications in sensorics. We have observed experimentally that in composites of P(VDF-TrFE) with barium-doped lead zirconate titanate (BPZT), the remanent polarization increases, while the coercive field substantially decreases in comparison with the pure polymer samples. Results of simulation in framework of the modified Weiss model have shown that the changes of the hysteresis loops characteristics are due to increase of the dielectric susceptibility of the composite as compared to pure PVDF-TrFE. This originates from the strong dispersion of the mean field constant α, which describes the feedback of the polarization on the electric field at the location of the dipoles and is closely related with the local increase of composite susceptibility in the vicinity the BPZT inclusions. This phenomenon effectively becomes macro-scale due to the long-range nature of the inhomogeneous elastic and electric fields occurring at the interfaces between the matrix and inclusions.

Despite the crucial role of lemming in the Arctic ecosystem, many aspects of its ecology are still unknown. The main challenge of studying lemming is that this rodent does not hibernate in winter and remains active under snow. To tackle this challenge, this paper presents a monitoring system based on near infrared. Design and implementation of a system that should work autonomously in the harsh arctic environment is really challenging. After developing the first version of the equipment, we installed three units at Bylot Island, Nunavut, Canada. Retrieved videos were promising and showed the great potential of this system in assisting ecologists to study the subnivean ecology of the Arctic. To the best of our knowledge, these are the first ever videos of lemming that have been recorded under snow in winter in the Arctic.

Subnivean life is an important part of the Arctic ecosystem but it has been little explored. Long, harsh winters in addition to remoteness have made direct studies in these hardly accessible areas very expensive and extremely hard. To tackle this problem, a low-power autonomous camera system (called ArcC ¸av) is developed for monitoring small mammals beneath the snow in the Canadian Arctic. ArcC ¸av is composed of several components, including a digital camera, a single board computer, a microcontroller board, and a motion detection sensor. Limited energy source, very cold temperature, darkness, and very long recording periods (several months) are major challenges that ArcC ¸av is designed to deal with. The performance of the developed system is evaluated in a real situation in the High Arctic. The field results show that ArcC ¸av can function well for an extended period of time on a battery at very low temperatures during the arctic winters. To the best of our knowledge, this is the first time that the life under snow has been filmed by a camera trap in the Arctic during winter. ArcC ¸av equips ecologists with a new means to explore and study subnivean life remotely. These observations can provide a foundation to answer some of questions that have puzzled animal ecologists for decades.