In recent decades, remanufacturing is perceived to be an environmentally friendly option due to the reduced consumption of materials, energy etc. It should be noted that whether the remanufacturing operations are undertaken by the original equipment manufacturers (OEMs) or outsourced to the remanufacturers, given the size and the growth of remanufactured products, many OEMs intend to fend off the potential cannibalization of new products sales through differentiating their quality levels from those of remanufactured ones by launching upgraded versions. To understand whether and how the product upgrading strategy impacts on optimal outcomes in the context of the remanufacturing operations undertaken by OEMs or third-party remanufacturers (TPRs), in this paper, we develop two models that highlight the OEM’s product upgrading strategy under the scenarios where (1) the OEM owns its remanufacturing operations in-house (Model O) or (2) remanufacturing operations are undertaken by a TPR (Model T). Among other results, we find that, from an economic performance perspective, it is more beneficial for the OEM to perform remanufacturing operations in-house; however, from an environmental sustainability perspective, such behavior is not always good for our environment. In particular, when the level of product upgrading is pronounced, the remanufacturing operations undertaken by the OEM are always detrimental to our environment, due to indulging in remanufacturing, as seen in Model O.

Magnetic tunnel junctions (MTJs) are pivotal for spintronic applications such as magnetoresistive memory and sensors. Two-dimensional van der Waals heterostructures offer a promising platform for miniaturizing MTJs while enabling twist-angle engineering of their properties. Here, we investigate the impact of twisting the insulating barrier layer on the performance of a van der Waals MTJ with the structure graphene/1T-VSe₂/h-BN/1T-VSe₂/graphene, where 1T-VSe₂ serves as the ferromagnetic electrodes and monolayer h-BN acts as the tunnel barrier. Using first-principles calculations based on density functional theory (DFT) combined with the non-equilibrium Green’s function (NEGF) formalism, we systematically calculate the spin-dependent transport properties for 18 distinct rotational alignments of the h-BN layer (0° to 172.4°). Our results reveal that the tunneling magnetoresistance (TMR) ratio exhibits dramatic, rotation-dependent variations, ranging from 2328% to 24608%. The maximum TMR occurs near 52.4°. Analysis shows that the twist angle modifies the d-orbital electronic states of interfacial V atoms in the 1T-VSe₂ layers and alters the spin polarization at the Fermi level, thereby governing the spin-dependent transmission through the barrier. This demonstrates that rotational manipulation of the h-BN layer provides an effective means to engineer the TMR and performance of van der Waals MTJs.

Magnetic tunnel junctions (MTJs) are pivotal for spintronic applications such as magneto resistive memory and sensors. Two-dimensional van der Waals heterostructures offer a promising platform for miniaturizing MTJs while enabling the twist-angle engineering of their properties. Here, we investigate the impact of twisting the insulating barrier layer on the performance of a van der Waals MTJ with the structure graphene/1T-VSe₂/h-BN/1T-VSe₂/graphene, where 1T-VSe₂ serves as the ferromagnetic electrodes and the monolayer h-BN acts as the tunnel barrier. Using first-principles calculations based on density functional theory (DFT) combined with the non-equilibrium Green’s function (NEGF) formalism, we systematically calculate the spin-dependent transport properties for 18 distinct rotational alignments of the h-BN layer (0° to 172.4°). Our results reveal that the tunneling magnetoresistance (TMR) ratio exhibits dramatic, rotation-dependent variations, ranging from 2328% to 24,608%. The maximum TMR occurs near 52.4°. An analysis shows that the twist angle modifies the d-orbital electronic states of interfacial V atoms in the 1T-VSe₂ layers and alters the spin polarization at the Fermi level, thereby governing the spin-dependent transmission through the barrier. This demonstrates that rotational manipulation of the h-BN layer provides an effective means to engineer the TMR and performance of van der Waals MTJs.