We introduce the idea of collisional models for Brownian particles, in which a particle is sequentially placed in contact with distinct thermal environments and external forces. Thermodynamic properties are exactly obtained, irrespective of the number of reservoirs involved. In the presence of external forces, the entropy production presents a bilinear form in which Onsager coefficients are exactly calculated. Analysis of Brownian engines based on sequential thermal switchings is proposed and considerations about their efficiencies are investigated, taking into account distinct external forces protocols. Our results shed light to an alternative route for obtaining efficient thermal engines based on finite times Brownian machines.

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We present a phenomenological analysis of the magnetoelastic properties of CeCoFeSi at temperatures close to the Néel transition temperature T . Using a Landau functional we provide a qualitative description of the thermal expansion, magnetostriction, magnetization and specific heat data. We show that the available experimental results (Correa et al 2016 J. Phys.: Condens. Matter 28 346003) are consistent with the presence of a structural transition at [Formula: see text] and a strong magnetoelastic coupling. The magnetoelastic coupling presents a Janus-faced effect: while the structural transition is shifted to higher temperatures as the magnetic field is increased, the resulting striction at low temperatures decreases. The strong magnetoelastic coupling and the proximity of the structural transition to the onset temperature for magnetic fluctuations, suggest that the transition could be an analogue of the tetragonal to orthorhombic observed in Fe-based pcnictides.

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Even at such a delicate moment in human history, this investigation was uninterrupted. My sincere acknowledgment for Malén Ailín Narambuena, Yordana Oropesa Henriquez and André de Pinho Vieira. This is not my investigation, it is our investigation.• To Eduardo Nascimento for the long hours of talks about nematics liquid crystals. In my head you were always my cosupervisor.• To Carlos Eduardo Fiore and his research group for the collaborations (especially Carlos Fernandez and Angel Leiva), I always felt like one of you.• For the Cuban community of Rio Pequeno for the aid received at the birth of my daughter.• To my family for their unconditional support.

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