For note, the effects of temperature and external demagnetising fields are easiest to calculate on NdFeB magnets that may be demagnetised as a result of such exposure if cgs units are used (Gauss, Tesla, MGOe) as cgs units allow faster production of new BH curves. When a new Intrinsic BH curve for Neodymium has been calculated (due to demagnetisation), at any point on the Intrinsic curve, note the corresponding value of H in Oersted and remove it from the corresponding B (in Gauss) of the Intrinsic curve and the resulting value is that of the value of B on the Normal curve (in Gauss) for the same H value. Using this, the Normal BH curve at different temperatures can be estimated if you already have an accurate ambient temperature BH curve for the “Neo” magnet (although this can be applied to any magnet material). Note the Br and Hci at ambient temperature (20 degrees C). If you want the curve at e.g. 120 degrees C, take the ambient temperature away to get the temperature difference (i.e. 120-20=100 degrees C).
Multiply this result by the temperature coefficients to give the percentage changes in Br and Hci to be expected. So Br will drop by 100x-0.12=-12% and Hci will drop by 100*-0.6 = 60%. Translate the Intrinsic BH curve shape so the curve starts and ends at the newly calculated Br and Hci and re-draw the new Intrinsic curve. This is the Intrinsic curve at 120 degrees C. Then use the calculation to convert from Intrinsic to Nomal in cgs units for any given H in Oersteds to generate the new Normal curve for the NdFeB. This new BH curve set can then be used for the calculations at 120 degrees C. Please note that this is an estimate as the temperature coefficients actually vary with temperature and the BH curve varies from batch to batch for any magnet, including Neodymium.